This library brings together research studies, clinical guidance, public-health data and other reference materials cited across our calculator pages, along with established Research Library references. Sources are grouped by topic. “Cited on” shows where a source currently appears; inclusion does not mean every figure or estimate on that page comes directly from that source. Check each calculator’s Methodology and sources section for context.
317 unique sources across 96 calculator-bearing pages, grouped into 14 topics. Catalog updated 19 July 2026.
Menstrual Cycles, Ovulation & Conception (50)
Abnormal Uterine Bleeding (opens source in a new tab)
Age and fecundability in a North American preconception cohort study. (opens source in a new tab)
Wesselink AK, Rothman KJ, Hatch EE, Mikkelsen EM, et al.. American journal of obstetrics and gynecology. 2017 Dec. DOI 10.1016/j.ajog.2017.09.002.
Cited on: Advanced Pregnancy Chance Calculator, Pregnancy Chance Calculator, Who Is the Father? Paternity Probability Calculator
Anticipatory Counseling Regarding Ovarian-Factor Fertility Decline (opens source in a new tab)
www.acog.org.
Cited on: Conception Chance Per Month Calculator
Appendix F: Classifications for Fertility Awareness-Based Methods (opens source in a new tab)
Cited on: BBT Time Adjustment Calculator
Changes with age in the level and duration of fertility in the menstrual cycle (opens source in a new tab)
Dunson DB, Colombo B, Baird DD. Human reproduction (Oxford, England). 2002 May. DOI 10.1093/humrep/17.5.1399.
Cited on: IUD Pregnancy Risk Calculator, Missed Pill Pregnancy Risk Calculator, One-Time Pregnancy Calculator: Percent Chance from a Single Encounter
Chronological aspects of ultrasonic, hormonal, and other indirect indices of ovulation (opens source in a new tab)
Ecochard R, Boehringer H, Rabilloud M, Marret H. BJOG. 2001 Aug. DOI 10.1111/j.1471-0528.2001.00194.x.
Day-specific probabilities of conception in fertile cycles resulting in spontaneous pregnancies. (opens source in a new tab)
Stirnemann JJ, Samson A, Bernard JP, Thalabard JC. Human reproduction (Oxford, England). 2013 Apr. DOI 10.1093/humrep/des449.
Cited on: Pregnancy Chance Calculator
Declines in Sexual Frequency among American Adults, 1989-2014 (opens source in a new tab)
Twenge JM, Sherman RA, Wells BE. Archives of Sexual Behavior. 2017. DOI 10.1007/s10508-017-0953-1.
Cited on: Advanced Pregnancy Chance Calculator, Contraceptive Risk Calculator
Diagnosis and treatment of luteal phase deficiency: a committee opinion (2021) – practice guidance | American Society for Reproductive Medicine | ASRM (opens source in a new tab)
www.asrm.org. 2021.
Cited on: Luteal Phase Length Calculator | Days Between Ovulation and Period, Menstrual Cycle Calculator – Cycle Day, Phases, Next Two Periods, Ovulation With PCOS: PCOS Ovulation Calculator
Effects of trying to conceive using an every-other-day strategy versus fertile window monitoring on stress: a 12-month randomized controlled trial (opens source in a new tab)
Martins MV, Fernandes J, Pedro J, Barros A, et al.. Human Reproduction. 2022 Nov. DOI 10.1093/humrep/deac228.
Established Research Library reference.
Evidence-based treatments for couples with unexplained infertility: a guideline (2020) | American Society for Reproductive Medicine | ASRM (opens source in a new tab)
Cited on: Clomiphene/Letrozole Ovulation Day Calculator, IUI Success Rate Calculator by Age and Attempt
Fertility Awareness-Based Methods of Contraception – Women's Health – MSD Manual Consumer Version (opens source in a new tab)
Cited on: Calculate Pregnancy Chance After Intercourse Without Contraception
Fertility Awareness-Based Methods of Family Planning (opens source in a new tab)
www.acog.org.
Cited on: BBT Ovulation Calculator: Ovulation Day From BBT, Can Ultrasound Tell Who the Father Is? Calculator, Cervical Mucus Fertile Window Calculator
Fertility evaluation of infertile women: a committee opinion (2021) (opens source in a new tab)
Cited on: Fertility Calculator by Age, Ovulation With PCOS: PCOS Ovulation Calculator
Fertility of Men and Women Aged 15-44 Years in the United States: National Survey of Family Growth, 2006-2010 (opens source in a new tab)
Martinez G, Daniels K, Chandra A. National Health Statistics Reports. 2012.
Established Research Library reference.
Findings from a mobile application-based cohort are consistent with established knowledge of the menstrual cycle, fertile window, and conception (opens source in a new tab)
Faust L, Bradley D, Landau E, Noddin K, et al.. Fertility and Sterility. 2019 Sep. DOI 10.1016/j.fertnstert.2019.05.008.
Cited on: One-Time Pregnancy Calculator: Percent Chance from a Single Encounter, Pregnancy Chance Calendar
FSRH — Fertility Awareness Methods (opens source in a new tab)
Cited on: Menstrual Cycle Calculator – Cycle Day, Phases, Next Two Periods
How Long Does a Period Last? What You Need to Know About Menstruation Length (opens source in a new tab)
How Many Days Between Periods? Normal and Irregular Menstruation (opens source in a new tab)
How regular is regular? An analysis of menstrual cycle regularity. (opens source in a new tab)
Creinin MD, Keverline S, Meyn LA. Contraception. 2004 Oct. DOI 10.1016/j.contraception.2004.04.012.
Cited on: Luteal Phase Length Calculator | Days Between Ovulation and Period
Infertility (opens source in a new tab)
www.nichd.nih.gov.
Cited on: Conception Chance Per Month Calculator
Infertility (opens source in a new tab)
www.who.int.
Cited on: Conception Chance Per Month Calculator
Infertility: Frequently Asked Questions (opens source in a new tab)
Cited on: Fertility Calculator by Age
Lactational amenorrhoea method for family planning (opens source in a new tab)
DOI 10.1002/14651858.cd001329.pub2/full.
Cited on: Postpartum Period Calculator: When Will My Fertility Return?
Likelihood of conception with a single act of intercourse: providing benchmark rates for assessment of post-coital contraceptives. (opens source in a new tab)
Wilcox AJ, Dunson DB, Weinberg CR, Trussell J, et al.. Contraception. 2001 Apr. DOI 10.1016/s0010-7824(01)00191-3.
Cited on: One-Time Pregnancy Calculator: Percent Chance from a Single Encounter
Manchester University NHS Foundation Trust: Clomid Patient Information Leaflet (opens source in a new tab)
Mucus observations in the fertile window: a better predictor of conception than timing of intercourse. (opens source in a new tab)
Bigelow JL, Dunson DB, Stanford JB, Ecochard R, et al.. Human reproduction (Oxford, England). 2004 Apr. DOI 10.1093/humrep/deh173.
Cited on: Cervical Mucus Fertile Window Calculator
Negative lifestyle is associated with a significant reduction in fecundity (opens source in a new tab)
Hassan MA, Killick SR. Fertility and Sterility. 2004. DOI 10.1016/j.fertnstert.2003.06.027.
Cited on: Advanced Pregnancy Chance Calculator, One-Time Pregnancy Calculator: Percent Chance from a Single Encounter, Pregnancy Chance Calculator
NHS Wales: Ovulation Induction with Oral Agents (Clomid & Letrozole) (opens source in a new tab)
Optimizing natural fertility: a committee opinion (2022) | American Society for Reproductive Medicine | ASRM (opens source in a new tab)
www.asrm.org. 2022.
Ovulation and conception | The Royal Women's Hospital (opens source in a new tab)
Ovulation Calculator (opens source in a new tab)
Cited on: Ovulation Calculator & Calendar 📅
Ovulation: Calculating, Process, Pain & Other Symptoms (opens source in a new tab)
Periods and fertility in the menstrual cycle – NHS (opens source in a new tab)
Cited on: Ovulation Calculator & Calendar 📅, Pregnancy Chance Per Day After Your Period
Real-world menstrual cycle characteristics of more than 600,000 menstrual cycles. (opens source in a new tab)
Bull JR, Rowland SP, Scherwitzl EB, Scherwitzl R, et al.. NPJ digital medicine. 2019. DOI 10.1038/s41746-019-0152-7.
The effectiveness of a fertility awareness based method to avoid pregnancy in relation to a couple's sexual behaviour during the fertile time: a prospective longitudinal study (opens source in a new tab)
Frank-Herrmann P, Heil J, Gnoth C, Toledo E, et al.. Human Reproduction. 2007 May. DOI 10.1093/humrep/dem003.
The interrelationship between sleep regulation and thermoregulation. (opens source in a new tab)
Krauchi K, Deboer T. Frontiers in bioscience (Landmark edition). 2010 Jan 1. DOI 10.2741/3636.
Cited on: BBT Time Adjustment Calculator
The Normal Menstrual Cycle and the Control of Ovulation (opens source in a new tab)
Cited on: Ovulation Calculator & Calendar 📅
The normal variabilities of the menstrual cycle (opens source in a new tab)
Cited on: Implantation Calculator & Calendar
The probability of conception on different days of the cycle with respect to ovulation: an overview. (opens source in a new tab)
Ferreira-Poblete A. Advances in contraception : the official journal of the Society for the Advancement of Contraception. 1997 Jun-Sep. DOI 10.1023/a:1006527232605.
Cited on: Due Date Calculator From Intercourse or Conception Date
The timing of the fertile window in the menstrual cycle: day specific estimates from a prospective study (opens source in a new tab)
Wilcox AJ, Dunson D, Baird DD. BMJ. 2000. DOI 10.1136/bmj.321.7271.1259.
Cited on 8 calculator pages
- Conception Date Calculator
- Due Date Calculator From Intercourse or Conception Date
- Late Period or Pregnant? Probability Calculator
- Menstrual Cycle Calculator – Cycle Day, Phases, Next Two Periods
- One-Time Pregnancy Calculator: Percent Chance from a Single Encounter
- Ovulation Calculator & Calendar 📅
- Pregnancy Chance Calculator
- Who Is the Father? Paternity Probability Calculator
The use of hormonal contraceptives in fertility treatments: a committee opinion (2024) (opens source in a new tab)
Cited on: AFC Percentile by Age Calculator (Antral Follicle Count)
Timing intercourse to achieve pregnancy: current evidence (opens source in a new tab)
Stanford JB, White GL, Hatasaka H. Obstetrics & Gynecology. 2002 Dec. DOI 10.1016/s0029-7844(02)02382-7.
Timing of Sexual Intercourse in Relation to Ovulation — Effects on the Probability of Conception, Survival of the Pregnancy, and Sex of the Baby (opens source in a new tab)
Allen J. Wilcox, Clarice R. Weinberg, Donna D. Baird, Wilcox AJ, et al.. New England Journal of Medicine. 1995 Dec 7. DOI 10.1056/nejm199512073332301.
Cited on 19 calculator pages
- Advanced Pregnancy Chance Calculator
- Calculate Pregnancy Chance After Intercourse Without Contraception
- Cervical Mucus Fertile Window Calculator
- Conception Date Calculator
- Conception date vs intercourse date explained
- Due Date Calculator From Intercourse or Conception Date
- Implantation Bleeding Calculator: Period vs Spotting
- IUD Pregnancy Risk Calculator
- Menstrual Cycle Calculator – Cycle Day, Phases, Next Two Periods
- Missed Pill Pregnancy Risk Calculator
- One-Time Pregnancy Calculator: Percent Chance from a Single Encounter
- OPK to Ovulation Calculator: LH Surge Timing
- Ovulation Calculator & Calendar 📅
- Plan B vs ella: Morning-After Pill Effectiveness Calculator
- Pregnancy Chance Calculator
- Pregnancy Chance Calendar
- Pregnancy Due Date Calculator
- Reverse Due Date Calculator: Find Your Conception Date
- Who Is the Father? Paternity Probability Calculator
Trying to Get Pregnant? Here’s When to Have Sex. (opens source in a new tab)
www.acog.org.
US of the Normal Endometrium | UW Emergency Radiology (opens source in a new tab)
faculty.washington.edu.
Variability in the phases of the menstrual cycle. (opens source in a new tab)
Fehring RJ, Schneider M, Raviele K. Journal of obstetric, gynecologic, and neonatal nursing : JOGNN. 2006 May-Jun. DOI 10.1111/j.1552-6909.2006.00051.x.
Cited on: Luteal Phase Length Calculator | Days Between Ovulation and Period
Volitional determinants and age-related decline in fecundability: a general population prospective cohort study in Denmark. (opens source in a new tab)
Rothman KJ, Wise LA, Sørensen HT, Riis AH, et al.. Fertility and sterility. 2013 Jun. DOI 10.1016/j.fertnstert.2013.02.040.
Cited on: Who Is the Father? Paternity Probability Calculator
What are the fertile days in the menstrual cycle? – Customer Support | Contact Us | Natural Cycles (opens source in a new tab)
Your First Period (opens source in a new tab)
Cited on: Menstrual Cycle Calculator – Cycle Day, Phases, Next Two Periods
Fertility by Age & Ovarian Reserve (19)
2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome: Summary (opens source in a new tab)
Cited on: AFC Percentile by Age Calculator (Antral Follicle Count), Ovulation With PCOS: PCOS Ovulation Calculator
A Validated Model of Serum Anti-Müllerian Hormone from Conception to Menopause (opens source in a new tab)
Thomas W. Kelsey, Phoebe Wright, Scott M. Nelson. PLoS ONE. 2011-7-15.
Cited on: AMH Levels by Age Calculator
Age-specific nomogram for the decline in antral follicle count throughout reproductive life (opens source in a new tab)
Cited on: AFC Percentile by Age Calculator (Antral Follicle Count)
ARCHITECT Estradiol assay instructions (archived manufacturer document) (opens source in a new tab)
Abbott / Internet Archive.
Cited on: Ovulation Calculator & Calendar 📅
Comparison of ovarian responsiveness tests with outcome of assisted reproductive technology – a retrospective analysis. (opens source in a new tab)
Selcuk S, Bilgic BE, Kilicci C, Kucukbas M, et al.. Archives of medical science : AMS. 2018 Jun. DOI 10.5114/aoms.2016.62447.
Cited on: Ovarian Reserve Index (ORPI) Calculator
DailyMed – MEDROXYPROGESTERONE ACETATE injection, suspension (opens source in a new tab)
Direct transport of progesterone from vagina to uterus. (opens source in a new tab)
Cicinelli E, de Ziegler D, Bulletti C, Matteo MG, et al.. Obstetrics and gynecology. 2000 Mar. DOI 10.1016/s0029-7844(99)00542-6.
Cited on: Progesterone Levels in Early Pregnancy: Calculator and Interpretation (ng/mL ↔ nmol/L)
Effect of small follicles on clinical pregnancy and multiple pregnancy rates in intrauterine insemination: a cohort study (opens source in a new tab)
Evaluation of Female Fertility-AMH and Ovarian Reserve Testing. (opens source in a new tab)
Cedars MI. The Journal of clinical endocrinology and metabolism. 2022 May 17. DOI 10.1210/clinem/dgac039.
Cited on: Euploid Embryo Probability Calculator
Fertility problems: assessment and treatment (CG156) (opens source in a new tab)
National Institute for Health and Care Excellence. NICE. 2013; last updated 2017.
Cited on: AMH Levels by Age: Interpreter, Cervical Mucus Fertile Window Calculator
Having a Baby After Age 35: How Aging Affects Fertility and Pregnancy (opens source in a new tab)
American College of Obstetricians and Gynecologists. ACOG.
Human ovarian reserve from conception to the menopause. (opens source in a new tab)
Wallace WH, Kelsey TW. PloS one. 2010 Jan 27. DOI 10.1371/journal.pone.0008772.
Cited on: Fertility Calculator by Age
Infertility and age: an unresolved issue (opens source in a new tab)
Hendershot GE, Mosher WD, Pratt WF. Family Planning Perspectives. 1982. DOI 10.2307/2134890.
Cited on: Contraceptive Risk Calculator
Intrauterine insemination: simultaneous with or 36 h after HCG? A randomized clinical trial (opens source in a new tab)
Ovarian Reserve Testing – Endotext – NCBI Bookshelf (opens source in a new tab)
www.ncbi.nlm.nih.gov.
Cited on: Euploid Embryo Probability Calculator
Prediction of high ovarian response to controlled ovarian hyperstimulation: anti-Müllerian hormone versus small antral follicle count (2-6 mm). (opens source in a new tab)
Aflatoonian A, Oskouian H, Ahmadi S, Oskouian L. Journal of assisted reproduction and genetics. 2009 Jun. DOI 10.1007/s10815-009-9319-5.
Cited on: Ovarian Reserve Index (ORPI) Calculator
Pretreatment antimüllerian hormone levels and outcomes of ovarian stimulation with gonadotropins/intrauterine insemination cycles (opens source in a new tab)
Testing and interpreting measures of ovarian reserve: a committee opinion (opens source in a new tab)
Practice Committee of the American Society for Reproductive Medicine. American Society for Reproductive Medicine; Fertility and Sterility. 2020. DOI 10.1016/j.fertnstert.2020.09.134.
Cited on: AFC Percentile by Age Calculator (Antral Follicle Count), AMH Levels by Age: Interpreter, IUI Success Rate Calculator by Age and Attempt
The best ovarian reserve marker to predict ovarian response following controlled ovarian hyperstimulation: a systematic review and meta-analysis. (opens source in a new tab)
Salemi F, Jambarsang S, Kheirkhah A, Salehi-Abargouei A, et al.. Systematic reviews. 2024 Dec 18. DOI 10.1186/s13643-024-02684-0.
Cited on: Ovarian Reserve Index (ORPI) Calculator
Assisted Reproduction & Fertility Treatment (25)
About Assisted Reproductive Technology (ART) (opens source in a new tab)
Cited on: Embryo Grade Success Rate Calculator
ART Success Rates (opens source in a new tab)
Cited on: Embryo Transfer Success Predictor Calculator, Fertility Calculator by Age
Blastocyst | Definition, Early Development, & Facts | Britannica (opens source in a new tab)
www.britannica.com.
Clomiphene: Uses, Dosage, Side Effects (opens source in a new tab)
Decisions to make about your embryos | HFEA (opens source in a new tab)
Cited on: Embryo Grade Success Rate Calculator
Double versus single intrauterine insemination (IUI) in stimulated cycles for subfertile couples (opens source in a new tab)
Cochrane Database of Systematic Reviews. 2021. DOI 10.1002/14651858.cd003854.pub2.
Effect of HCG-Triggered Ovulation on Pregnancy Outcomes in Intrauterine Insemination: An Analysis of 5,610 First IUI Natural Cycles With Donor Sperm in China (opens source in a new tab)
Frontiers in Endocrinology. 2020. DOI 10.3389/fendo.2020.00423.
Effectiveness of spontaneous ovulation as monitored by urinary luteinising hormone versus induced ovulation by administration of human chorionic gonadotrophin in couples undergoing gonadotrophin‐stimulated intrauterine insemination: a randomised controlled trial (opens source in a new tab)
BJOG: An International Journal of Obstetrics & Gynaecology. 2019. DOI 10.1111/1471-0528.15830.
ESHRE Guideline on Ovarian Stimulation for IVF/ICSI (opens source in a new tab)
European Society of Human Reproduction and Embryology. ESHRE. 2025 update, version 2.2 (November 2025).
Cited on: AMH Levels by Age: Interpreter
Evidence-based guideline: Unexplained Infertility (opens source in a new tab)
ESHRE.
Cited on: Clomiphene/Letrozole Ovulation Day Calculator, IUI Success Rate Calculator by Age and Attempt
Fresh transfer outcome predicts the success of a subsequent frozen transfer utilizing blastocysts of the same cohort. (opens source in a new tab)
Doherty LF, Martin JR, Kayisli U, Sakkas D, et al.. Reproductive biomedicine online. 2014 Feb. DOI 10.1016/j.rbmo.2013.09.030.
Frontiers | Preparation of the Endometrium for Frozen Embryo Transfer: A Systematic Review (opens source in a new tab)
Guidance on the limits to the number of embryos to transfer: a committee opinion (2021) (opens source in a new tab)
Cited on: Embryo Grade Success Rate Calculator
Intra-uterine insemination for unexplained subfertility (opens source in a new tab)
Cochrane Database of Systematic Reviews. 2006. DOI 10.1002/14651858.cd001838.pub3.
Intrauterine insemination (IUI) – NHS – NHS (opens source in a new tab)
IUI (Intrauterine Insemination): Procedure & Results (opens source in a new tab)
Letrozole, Gonadotropin, or Clomiphene for Unexplained Infertility (opens source in a new tab)
New England Journal of Medicine. 2015. DOI 10.1056/nejmoa1414827.
Cited on: Chance of Twins Calculator, Clomiphene/Letrozole Ovulation Day Calculator
Optimal timing for intrauterine insemination (IUI) after administering HCG in ovulation induction IUI cycles (opens source in a new tab)
Cited on: IUI Due Date Calculator
Performance of ovarian response prediction index (ORPI) in predicting ovarian response and livebirth in the in-vitro fertilisation cycle using a standard stimulation with corifollitropin alpha in a GnRH antagonist protocol. (opens source in a new tab)
Ng DYT, Ko JKY, Li HWR, Lau EYL, et al.. Human fertility (Cambridge, England). 2020 Aug 12. DOI 10.1080/14647273.2020.1805517.
Cited on: Ovarian Reserve Index (ORPI) Calculator
Preimplantation genetic testing for aneuploidy (PGT-A)-a single-center experience. (opens source in a new tab)
Nair J, Shetty S, Kasi CI, Thondehalmath N, et al.. Journal of assisted reproduction and genetics. 2022 Mar. DOI 10.1007/s10815-022-02413-3.
Cited on: Euploid Embryo Probability Calculator
SART Outcome Tables (opens source in a new tab)
Cited on: Embryo Grade Success Rate Calculator
The effect of endometrial thickness on pregnancy outcomes of frozen-thawed embryo transfer cycles which underwent hormone replacement therapy. (opens source in a new tab)
Shaodi Z, Qiuyuan L, Yisha Y, Cuilian Z. PloS one. 2020. DOI 10.1371/journal.pone.0239120.
The nature of aneuploidy with increasing age of the female partner: a review of 15,169 consecutive trophectoderm biopsies evaluated with comprehensive chromosomal screening. (opens source in a new tab)
Franasiak JM, Forman EJ, Hong KH, Werner MD, et al.. Fertility and sterility. 2014 Mar. DOI 10.1016/j.fertnstert.2013.11.004.
Cited on: Euploid Embryo Probability Calculator
The use of preimplantation genetic testing for aneuploidy (PGT-A): a committee opinion. (opens source in a new tab)
Practice Committees of the American Society for Reproductive Medicine and the Society for Assisted Reproductive Technology. Electronic address: [email protected], Practice Committees of the American Society for Reproductive Medicine and the Society for Assisted Reproductive Technology. Fertility and sterility. 2018 Mar. DOI 10.1016/j.fertnstert.2018.01.002.
Cited on: Euploid Embryo Probability Calculator
University of South Florida IUI patient handbook (PDF) (opens source in a new tab)
Cited on: IUI Due Date Calculator
Contraception, Emergency Contraception & Return to Fertility (45)
Access to Emergency Contraception (opens source in a new tab)
www.acog.org.
Cited on: IUD Pregnancy Risk Calculator
Appendix D: Contraceptive Effectiveness (opens source in a new tab)
Cited on: Plan B vs ella: Morning-After Pill Effectiveness Calculator
Appendix J: Classifications for Emergency Contraception (opens source in a new tab)
Cited on: Missed Pill Pregnancy Risk Calculator
Benchmark pregnancy rates and the assessment of post-coital contraceptives: an update. (opens source in a new tab)
Li D, Wilcox AJ, Dunson DB. Contraception. 2015 Apr. DOI 10.1016/j.contraception.2015.01.002.
Cited on: Who Is the Father? Paternity Probability Calculator
CDC missed-pill chart (2024) (opens source in a new tab)
Cited on: Missed Pill Pregnancy Risk Calculator
Combined Hormonal Birth Control: Pill, Patch, and Ring (opens source in a new tab)
Cited on: Get Pregnant After Stopping the Pill Calculator, Postpartum Ovulation & Fertility Calculator
Combined Hormonal Contraceptives (opens source in a new tab)
Cited on: Missed Pill Pregnancy Risk Calculator
Condom Use and HIV Prevention (opens source in a new tab)
Cited on: How Effective is Using Two Contraceptive Methods at Once?, Top Contraceptive Method Combinations for Maximum Protection
Condoms fact sheet (opens source in a new tab)
World Health Organization.
Cited on: Top Contraceptive Method Combinations for Maximum Protection
Contraception and Birth Control Methods (opens source in a new tab)
Cited on: IUD Pregnancy Risk Calculator, Late Period or Pregnant? Probability Calculator
Contraceptive failure in the United States (opens source in a new tab)
Trussell J. Contraception. 2011. DOI 10.1016/j.contraception.2011.01.021.
Cited on 7 calculator pages
- Advanced Pregnancy Chance Calculator
- Contraceptive Risk Calculator
- How Effective is Using Two Contraceptive Methods at Once?
- One-Time Pregnancy Calculator: Percent Chance from a Single Encounter
- Pregnancy Chance Calculator
- Pregnancy Chance Calendar
- Top Contraceptive Method Combinations for Maximum Protection
Effectiveness of Family Planning Methods (opens source in a new tab)
Centers for Disease Control and Prevention.
Cited on: Top Contraceptive Method Combinations for Maximum Protection
Emergency Contraception (opens source in a new tab)
Cited on: Calculate Pregnancy Chance After Intercourse Without Contraception
Emergency Contraception (opens source in a new tab)
www.acog.org.
Cited on: Calculate Pregnancy Chance After Intercourse Without Contraception, IUD Pregnancy Risk Calculator
Emergency Contraception (opens source in a new tab)
Cited on: Calculate Pregnancy Chance After Intercourse Without Contraception, Missed Pill Pregnancy Risk Calculator, Plan B vs ella: Morning-After Pill Effectiveness Calculator
Emergency contraception (opens source in a new tab)
www.who.int.
Cited on: Calculate Pregnancy Chance After Intercourse Without Contraception, Missed Pill Pregnancy Risk Calculator, Plan B vs ella: Morning-After Pill Effectiveness Calculator
Estimates of contraceptive failure from the 2002 National Survey of Family Growth (opens source in a new tab)
Kost K, Singh S, Vaughan B, Trussell J, et al.. Contraception. 2008 Jan. DOI 10.1016/j.contraception.2007.09.013.
Cited on: Advanced Pregnancy Chance Calculator, Contraceptive Risk Calculator, Pregnancy Chance Calculator
FSRH Clinical Guideline: Contraception After Pregnancy (January 2017, amended October 2020) (opens source in a new tab)
FSRH Clinical Guideline: Intrauterine Contraception (opens source in a new tab)
Faculty of Sexual & Reproductive Healthcare.
Cited on: Get Pregnant After IUD Removal: Timeline Calculator
FSRH Guideline: Emergency Contraception (opens source in a new tab)
Faculty of Sexual & Reproductive Healthcare.
Cited on: Plan B vs ella: Morning-After Pill Effectiveness Calculator
FSRH Guideline: Progestogen-only Implant (opens source in a new tab)
Faculty of Sexual & Reproductive Healthcare. FSRH. February 2021; amended July 2023.
FSRH POP guideline (incl. late-pill thresholds) (opens source in a new tab)
Cited on: Missed Pill Pregnancy Risk Calculator
Intrauterine Contraception (opens source in a new tab)
Long-Acting Reversible Contraception (LARC): Intrauterine Device (IUD) and Implant (opens source in a new tab)
www.acog.org.
Cited on: IUD Pregnancy Risk Calculator
Long-Acting Reversible Contraception: Implants and Intrauterine Devices (Practice Bulletin No. 186) (opens source in a new tab)
American College of Obstetricians and Gynecologists. ACOG. November 2017.
Cited on: Get Pregnant After Implant Removal Calculator, Get Pregnant After IUD Removal: Timeline Calculator, IUD Pregnancy Risk Calculator
Medical eligibility criteria for contraceptive use (opens source in a new tab)
Cited on: Get Pregnant After IUD Removal: Timeline Calculator
Nexplanon (opens source in a new tab)
NEXPLANON (etonogestrel implant) Highlights of Prescribing Information (opens source in a new tab)
U.S. Food and Drug Administration. FDA. 2026.
NHS 111 Wales – Pregnancy Guide (opens source in a new tab)
111.wales.nhs.uk.
Cited on: Plan B vs ella: Morning-After Pill Effectiveness Calculator
Nonoxynol-9 ineffective in preventing HIV infection (opens source in a new tab)
www.who.int.
Cited on: Top Contraceptive Method Combinations for Maximum Protection
PARAGARD T 380A — copper intrauterine device (opens source in a new tab)
Postpartum Birth Control (opens source in a new tab)
www.acog.org.
Cited on: Breastfeeding (LAM) Eligibility & Risk Calculator, Postpartum Ovulation & Fertility Calculator
Primary Prevention Methods (opens source in a new tab)
Cited on: Top Contraceptive Method Combinations for Maximum Protection
Progestin-Only Hormonal Birth Control: Pill and Injection (opens source in a new tab)
Selected practice recommendations for contraceptive use (opens source in a new tab)
www.who.int.
Standards and Guidelines | CoSRH (opens source in a new tab)
www.cosrh.org.
The risk of pregnancy after tubal sterilization: findings from the U.S. Collaborative Review of Sterilization (opens source in a new tab)
Peterson HB, Xia Z, Hughes JM, Wilcox LS, et al.. American journal of obstetrics and gynecology. 1996 Apr. DOI 10.1016/s0002-9378(96)70658-0.
Cited on: Tubal Ligation Failure Risk Calculator
The Top 5 Questions I’m Asked About Emergency Contraception (opens source in a new tab)
These highlights do not include all the information needed to use MIRENA safely and effectively. See full prescribing information for MIRENA. MIRENA (levonorgestrel-releasing intrauterine system) Initial U.S. Approval: 2000 (opens source in a new tab)
U.S. Selected Practice Recommendations for Contraceptive Use, 2024 (opens source in a new tab)
Centers for Disease Control and Prevention. MMWR Recommendations and Reports. 2024.
Cited on 10 calculator pages
- Birth Control Switch Protection-Gap Calculator
- Contraceptive Risk Calculator
- Get Pregnant After Implant Removal Calculator
- Get Pregnant After IUD Removal: Timeline Calculator
- Get Pregnant After Stopping the Pill Calculator
- How Effective is Using Two Contraceptive Methods at Once?
- IUD Pregnancy Risk Calculator
- Missed Pill Pregnancy Risk Calculator
- Top Contraceptive Method Combinations for Maximum Protection
- Tubal Ligation Failure Risk Calculator
Ulipristal acetate versus levonorgestrel for emergency contraception: a randomised non-inferiority trial and meta-analysis (opens source in a new tab)
DOI 10.1016/s0140-6736(10)60101-8.
Cited on: Calculate Pregnancy Chance After Intercourse Without Contraception, Missed Pill Pregnancy Risk Calculator, Plan B vs ella: Morning-After Pill Effectiveness Calculator
Vasectomy occlusion techniques for male sterilization (opens source in a new tab)
Cochrane Database of Systematic Reviews. 2007. DOI 10.1002/14651858.cd003991.pub3.
Cited on: Vasectomy Failure Risk Calculator
What Condom Users Should Not Do | Family Planning (opens source in a new tab)
fphandbook.org.
Cited on: How Effective is Using Two Contraceptive Methods at Once?, Top Contraceptive Method Combinations for Maximum Protection
Which Kind of Emergency Contraception Should I Use? (opens source in a new tab)
Cited on: Calculate Pregnancy Chance After Intercourse Without Contraception
WHO Family Planning effectiveness table (opens source in a new tab)
Cited on: Vasectomy Failure Risk Calculator
Pregnancy Testing, hCG & Early-Pregnancy Hormones (26)
Association of HCG Level with Ultrasound Visualization of the Gestational Sac in Early Viable Pregnancies. (opens source in a new tab)
Park KE, Latack KR, Vestal NL, Ingles SA, et al.. Reproductive sciences (Thousand Oaks, Calif.). 2023 Dec. DOI 10.1007/s43032-023-01308-7.
Cited on: Early Ultrasound Visibility and Best Scan Date Calculator
Bleeding and/or pain in early pregnancy | RCOG (opens source in a new tab)
Cited on: Progesterone Levels in Early Pregnancy: Calculator and Interpretation (ng/mL ↔ nmol/L), Subchorionic Hematoma Risk Calculator by Week and Size
Comparison of analytical sensitivity and women’s interpretation of home pregnancy tests (opens source in a new tab)
Sarah Johnson, Michael Cushion, Sharon Bond. Clinical Chemistry and Laboratory Medicine (CCLM). 2015-1-1. DOI 10.1515/cclm-2014-0643/html.
Cited on: Implantation Bleeding Calculator: Period vs Spotting
Differences in Serum Human Chorionic Gonadotropin Rise in Early Pregnancy by Race and Value at Presentation. (opens source in a new tab)
Barnhart KT, Guo W, Cary MS, Morse CB, et al.. Obstetrics and gynecology. 2016 Sep. DOI 10.1097/aog.0000000000001568.
Cited on: hCG Calculator: Doubling Time, Rise & Multi-Draw Chart, hCG Rise Calculator: Compare Two Blood Tests
Doing a pregnancy test – NHS (opens source in a new tab)
Cited on: Calculate Pregnancy Chance After Intercourse Without Contraception, Ovulation With PCOS: PCOS Ovulation Calculator, Postpartum Ovulation & Fertility Calculator
Early Pregnancy Diagnosis – StatPearls – NCBI Bookshelf (opens source in a new tab)
Cited on: hCG Calculator: Doubling Time, Rise & Multi-Draw Chart, Twin and Triplet hCG Doubling Time Calculator
Following declining human chorionic gonadotropin values in pregnancies of unknown location: when is it safe to stop? (opens source in a new tab)
Cameron KE, Senapati S, Sammel MD, Chung K, et al.. Fertility and sterility. 2016 Apr. DOI 10.1016/j.fertnstert.2015.11.050.
Cited on: Residual hCG or New Pregnancy Calculator
Further observations on serial human chorionic gonadotropin patterns in ectopic pregnancies and spontaneous abortions. (opens source in a new tab)
Kadar N, Romero R. Fertility and sterility. 1988 Aug. DOI 10.1016/s0015-0282(16)60089-4.
Cited on: Residual hCG or New Pregnancy Calculator
HCG blood test – quantitative | UCSF Health (opens source in a new tab)
Cited on: Beta hCG Level Checker by Week
HCG blood test – quantitative: MedlinePlus Medical Encyclopedia (opens source in a new tab)
Cited on: Beta hCG Calculator | How Many Weeks Pregnant?, Beta hCG Level Checker by Week
hCG levels | healthdirect (opens source in a new tab)
Home pregnancy tests: Can you trust the results? (opens source in a new tab)
Cited on: Conception date vs intercourse date explained, IUI Due Date Calculator
Home Use Tests: Pregnancy (opens source in a new tab)
U.S. Food and Drug Administration.
Cited on: Pregnancy Chance Calendar
Human chorionic gonadotropin (hCG) test – pregnancy | healthdirect (opens source in a new tab)
Cited on: Implantation Calculator & Calendar
Human Chorionic Gonadotropin – StatPearls – NCBI Bookshelf (opens source in a new tab)
www.ncbi.nlm.nih.gov.
Cited on: hCG Rise Calculator: Compare Two Blood Tests, Pregnancy Test Line Progression Calculator
Pregnancy Test: When To Take, Types & Accuracy (opens source in a new tab)
Cited on: Due Date Calculator From Intercourse or Conception Date, Implantation Calculator & Calendar
Pregnancy Tests Fact Sheet (opens source in a new tab)
Office on Women's Health, U.S. Department of Health and Human Services.
Reference ranges and determinants of total hCG levels during pregnancy: the Generation R Study. (opens source in a new tab)
Korevaar TI, Steegers EA, de Rijke YB, Schalekamp-Timmermans S, et al.. European journal of epidemiology. 2015 Sep. DOI 10.1007/s10654-015-0039-0.
Serum human chorionic gonadotropin levels throughout normal pregnancy. (opens source in a new tab)
Braunstein GD, Rasor J, Danzer H, Adler D, et al.. American journal of obstetrics and gynecology. 1976 Nov 15. DOI 10.1016/0002-9378(76)90518-4.
Strips of Hope: Accuracy of Home Pregnancy Tests and New Developments. (opens source in a new tab)
Gnoth C, Johnson S. Geburtshilfe und Frauenheilkunde. 2014 Jul. DOI 10.1055/s-0034-1368589.
Symptoms of pregnancy: What happens first (opens source in a new tab)
Cited on: Am I Pregnant? A Calculator to Estimate Your Percentage Chance
The events of early pregnancy: prying open the black box (opens source in a new tab)
Ultrasound in Obstetrics & Gynecology. 2012. DOI 10.1002/uog.12329.
Cited on: Implantation Calculator & Calendar
Time of implantation of the conceptus and loss of pregnancy. (opens source in a new tab)
Allen J. Wilcox, Donna Day Baird, Clarice R. Weinberg, Wilcox AJ, et al.. The New England journal of medicine. 1999 Jun 10. DOI 10.1056/nejm199906103402304.
Cited on 6 calculator pages
Urinary hCG patterns during the week following implantation (opens source in a new tab)
Nepomnaschy PA, Weinberg CR, Wilcox AJ, Baird DD. Human reproduction (Oxford, England). 2008 Feb. DOI 10.1093/humrep/dem397.
Cited on: Implantation Calculator & Calendar
What Is hCG? (opens source in a new tab)
β-Human Chorionic Gonadotropin Dynamics in Early Gestational Events: A Practical and Updated Reappraisal. (opens source in a new tab)
Larraín D, Caradeux J. Obstetrics and gynecology international. 2024. DOI 10.1155/2024/8351132.
Cited on: hCG Calculator: Doubling Time, Rise & Multi-Draw Chart
Pregnancy Dating, Gestational Age & Due Dates (15)
28 weeks pregnant guide – Best Start in Life – NHS (opens source in a new tab)
Cited on: IUI Due Date Calculator
Accurate pregnancy dating and estimated due date (opens source in a new tab)
Safer Care Victoria.
Cited on: Pregnancy Due Date Calculator
Committee Opinion No. 700: Methods for Estimating the Due Date (opens source in a new tab)
Obstetrics & Gynecology. 2017 May. DOI 10.1097/aog.0000000000002046.
Cited on 11 calculator pages
- Can Ultrasound Tell Who the Father Is? Calculator
- Clomiphene/Letrozole Ovulation Day Calculator
- Conception Date Calculator
- CRL Calculator | Crown-Rump Length to GA & EDD
- Due Date Calculator From Intercourse or Conception Date
- Gestational Age Calculator: How Far Along Am I?
- IUI Due Date Calculator
- Pregnancy Chance Calendar
- Pregnancy Due Date Calculator
- Reverse Due Date Calculator: Find Your Conception Date
- Twin & Triplet Due Date Calculator
Dating scan (opens source in a new tab)
Duration of human singleton pregnancy. A population-based study (opens source in a new tab)
Bergsjø P, Denman DW 3rd, Hoffman HJ, Meirik O. Acta Obstetricia et Gynecologica Scandinavica. 1990. DOI 10.3109/00016349009028681.
Established Research Library reference.
Estimating due date (EDD) (opens source in a new tab)
South Eastern Sydney Local Health District.
Cited on: IUI Due Date Calculator, Pregnancy Due Date Calculator
Fetal crown-rump length: reevaluation of relation to menstrual age (5-18 weeks) with high-resolution real-time US. (opens source in a new tab)
Hadlock FP, Shah YP, Kanon DJ, Lindsey JV. Radiology. 1992 Feb. DOI 10.1148/radiology.182.2.1732970.
Gestational Age – Pediatrics – MSD Manual Professional Edition (opens source in a new tab)
Cited on: IUI Due Date Calculator
International standards for early fetal size and pregnancy dating based on ultrasound measurement of crown-rump length in the first trimester of pregnancy. (opens source in a new tab)
Papageorghiou AT, Kennedy SH, Salomon LJ, Ohuma EO, et al.. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 2014 Dec. DOI 10.1002/uog.13448.
Pregnancy Dating (opens source in a new tab)
Cited on: Conception Date Calculator, Pregnancy Due Date Calculator, Reverse Due Date Calculator: Find Your Conception Date
Pregnancy due date calculator – NHS (opens source in a new tab)
Recommendations | Antenatal care | Guidance (opens source in a new tab)
Cited on: IUI Due Date Calculator
Robinson Crown–Rump Length Chart (opens source in a new tab)
BC Women's Hospital and Health Centre.
Cited on: Nuchal Translucency Calculator | NT Percentile & NT From CRL
The length of human pregnancy as calculated by ultrasonographic measurement of the fetal biparietal diameter (opens source in a new tab)
Kieler H, Axelsson O, Nilsson S, Waldenström U. Ultrasound in Obstetrics & Gynecology. 1995 Nov. DOI 10.1046/j.1469-0705.1995.06050353.x.
Established Research Library reference.
When Pregnancy Goes Past Your Due Date (opens source in a new tab)
Ultrasound, Fetal Growth & Doppler (17)
A critical evaluation of sonar "crown-rump length" measurements. (opens source in a new tab)
Robinson HP, Fleming JE. British journal of obstetrics and gynaecology. 1975 Sep. DOI 10.1111/j.1471-0528.1975.tb00710.x.
AIUM Practice Parameter for the Performance of Standard Diagnostic Obstetric Ultrasound Examinations (opens source in a new tab)
Cited on: MSD Calculator | Mean Sac Diameter to Early Gestational Age
Embryonic heart rate in the early first trimester: what rate is normal? (opens source in a new tab)
Doubilet PM, Benson CB. Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine. 1995 Jun. DOI 10.7863/jum.1995.14.6.431.
Cited on: Live Birth and Chromosome Risk Calculator, Miscarriage Risk Calculator | Week and day odds
Fetal Growth Restriction (opens source in a new tab)
Fetal Measurements | BMUS (opens source in a new tab)
First-Trimester Obstetric Ultrasound (opens source in a new tab)
Cited on: MSD Calculator | Mean Sac Diameter to Early Gestational Age
Gestational Sac Evaluation (opens source in a new tab)
StatPearls / NCBI Bookshelf.
Cited on: MSD Calculator | Mean Sac Diameter to Early Gestational Age
Guidelines for the Performance of First Trimester Ultrasound (opens source in a new tab)
Australasian Society for Ultrasound in Medicine.
Cited on: MSD Calculator | Mean Sac Diameter to Early Gestational Age
How Your Fetus Grows During Pregnancy (opens source in a new tab)
New charts for ultrasound dating of pregnancy and assessment of fetal growth: longitudinal data from a population‐based cohort study (opens source in a new tab)
Ultrasound in Obstetrics & Gynecology. 2008. DOI 10.1002/uog.5225.
Practice guidelines for performance of the routine mid‐trimester fetal ultrasound scan (opens source in a new tab)
L. J. Salomon, Z. Alfirevic, V. Berghella. Ultrasound in Obstetrics & Gynecology. 2011-1. DOI 10.1002/uog.8831.
Cited on: BPD Gestational Age Calculator
Radiopaedia article on fetal heart beat (opens source in a new tab)
Cited on: IUI Due Date Calculator
Radiopaedia: Gestational sac (opens source in a new tab)
Cited on: MSD Calculator | Mean Sac Diameter to Early Gestational Age
Radiopaedia: Mean sac diameter (opens source in a new tab)
Cited on: MSD Calculator | Mean Sac Diameter to Early Gestational Age
The Role of Transvaginal Ultrasonography in Evaluating the Endometrium of Women With Postmenopausal Bleeding (opens source in a new tab)
www.acog.org.
Ultrasound Exams (opens source in a new tab)
Cited on: IUI Due Date Calculator
Ultrasound in the First Trimester (opens source in a new tab)
Ultrasound in Obstetrics and Gynecology: A Practical Approach (GLOWM).
Cited on: MSD Calculator | Mean Sac Diameter to Early Gestational Age
Twins & Multiple Pregnancy (15)
Dizygotic twinning (opens source in a new tab)
DOI 10.1093/humupd/dmm036.
Cited on: Chance of Twins Calculator
Familial incidence of twinning. (opens source in a new tab)
Parisi P, Gatti M, Prinzi G, Caperna G. Nature. 1983 Aug 18-24. DOI 10.1038/304626a0.
Cited on: Chance of Twins Calculator
First trimester β-hCG and estradiol levels in singleton and twin pregnancies after assisted reproduction. (opens source in a new tab)
Póvoa A, Xavier P, Matias A, Blickstein I. Journal of perinatal medicine. 2018 Oct 25. DOI 10.1515/jpm-2017-0132.
ISUOG Practice Guidelines: role of ultrasound in twin pregnancy. (Dating twin pregnancies). (opens source in a new tab)
Mode of delivery in multiple pregnancies (opens source in a new tab)
Cited on: IUI Due Date Calculator
Monochorionic Twin Pregnancy, Management – 2024 Partial Update (Green-top Guideline No. 51) | RCOG (opens source in a new tab)
www.rcog.org.uk. 2024.
Cited on: Twin & Triplet Due Date Calculator, Twin Growth Discordance Calculator (% Difference), Vanishing Twin Probability Calculator (by Week and Twin Type)
Multifetal Gestations Twin Triplet and Higher-Order Multifetal Pregnancies (opens source in a new tab)
Cited on: IUI Due Date Calculator, Vanishing Twin Probability Calculator (by Week and Twin Type)
Multiple gestation associated with infertility therapy: a committee opinion (2022) | American Society for Reproductive Medicine | ASRM (opens source in a new tab)
Cited on: Clomiphene/Letrozole Ovulation Day Calculator, IUI Success Rate Calculator by Age and Attempt
Overview | Twin and triplet pregnancy | Guidance (opens source in a new tab)
Cited on: Twin & Triplet Due Date Calculator, Vanishing Twin Probability Calculator (by Week and Twin Type)
Protocol for Ultrasound Scans in Multiple Pregnancies (opens source in a new tab)
Cited on: Vanishing Twin Probability Calculator (by Week and Twin Type)
Relationship of maternal body mass index and height to twinning. (opens source in a new tab)
Reddy UM, Branum AM, Klebanoff MA. Obstetrics and gynecology. 2005 Mar. DOI 10.1097/01.aog.0000153491.09525.dd.
Cited on: Chance of Twins Calculator
Role of early serum beta human chorionic gonadotropin measurement in predicting multiple pregnancy and pregnancy wastage in an in vitro ET fertilization cycle. (opens source in a new tab)
Singh N, Begum AA, Malhotra N, Bahadur A, et al.. Journal of human reproductive sciences. 2013 Jul. DOI 10.4103/0974-1208.121425.
Timing of birth in uncomplicated twin pregnancies — Good practice point (opens source in a new tab)
Safer Care Victoria.
Cited on: Twin & Triplet Due Date Calculator
Twin Peaks: more twinning in humans than ever before (opens source in a new tab)
Cited on: Chance of Twins Calculator
Variations in the maternal age effect on twinning rates: the Nordic experience. (opens source in a new tab)
Fellman J, Eriksson AW. Twin research and human genetics : the official journal of the International Society for Twin Studies. 2005 Oct. DOI 10.1375/183242705774310178.
Cited on: Chance of Twins Calculator
Miscarriage, Stillbirth & Pregnancy Loss (27)
A systematic review to calculate background miscarriage rates using life table analysis. (opens source in a new tab)
Ammon Avalos L, Galindo C, Li DK. Birth defects research. Part A, Clinical and molecular teratology. 2012 Jun. DOI 10.1002/bdra.23014.
Cited on: Live Birth and Chromosome Risk Calculator, Miscarriage Risk Calculator | Week and day odds, Pregnancy Announcement Risk-by-Date Calculator
About Stillbirth (opens source in a new tab)
Cited on: Stillbirth Risk Calculator
ACOG Practice Bulletin No. 200: Early Pregnancy Loss. (opens source in a new tab)
American College of Obstetricians and Gynecologists' Committee on Practice Bulletins—Gynecology. Obstetrics and gynecology. 2018 Nov. DOI 10.1097/aog.0000000000002899.
Bleeding During Pregnancy (opens source in a new tab)
www.acog.org.
Cited on: Implantation Bleeding Calculator: Period vs Spotting
Care of late intrauterine fetal death and stillbirth (Green-top Guideline No. 55) | RCOG (opens source in a new tab)
Cited on: Stillbirth Risk Calculator
Diagnostic criteria for nonviable pregnancy early in the first trimester. (opens source in a new tab)
Doubilet PM, Benson CB, Bourne T, Blaivas M, et al.. The New England journal of medicine. 2013 Oct 10. DOI 10.1056/nejmra1302417.
Cited on: Chance of Live Birth Calculator, Miscarriage Risk Calculator | Week and day odds, MSD Calculator | Mean Sac Diameter to Early Gestational Age
Early pregnancy bleeding (opens source in a new tab)
Cited on: Beta hCG Calculator | How Many Weeks Pregnant?, Twin and Triplet hCG Doubling Time Calculator
Early Pregnancy Loss (opens source in a new tab)
Cited on: Progesterone Levels in Early Pregnancy: Calculator and Interpretation (ng/mL ↔ nmol/L), Subchorionic Hematoma Risk Calculator by Week and Size
Early Pregnancy Loss (Spontaneous Abortion) – StatPearls – NCBI Bookshelf (opens source in a new tab)
Cited on: Chance of Live Birth Calculator, Miscarriage Risk Calculator | Week and day odds
Ectopic Pregnancy (opens source in a new tab)
Cited on: Early Ultrasound Visibility and Best Scan Date Calculator, Residual hCG or New Pregnancy Calculator
Ectopic pregnancy and miscarriage: diagnosis and initial management (NICE guideline NG126) (opens source in a new tab)
www.nice.org.uk.
Cited on 8 calculator pages
- CRL Calculator | Crown-Rump Length to GA & EDD
- hCG Calculator: Doubling Time, Rise & Multi-Draw Chart
- hCG Rise Calculator: Compare Two Blood Tests
- Implantation Bleeding Calculator: Period vs Spotting
- Miscarriage Risk Calculator | Week and day odds
- Progesterone Levels in Early Pregnancy: Calculator and Interpretation (ng/mL ↔ nmol/L)
- Subchorionic Hematoma Risk Calculator by Week and Size
- Vanishing Twin Probability Calculator (by Week and Twin Type)
First Trimester Bleeding (opens source in a new tab)
First Trimester Bleeding: Evaluation and Management (opens source in a new tab)
Management of Stillbirth (opens source in a new tab)
Cited on: Live Birth and Chromosome Risk Calculator, Stillbirth Risk Calculator
Maternal age and fetal loss: population based register linkage study. (opens source in a new tab)
Nybo Andersen AM, Wohlfahrt J, Christens P, Olsen J, et al.. BMJ (Clinical research ed.). 2000 Jun 24. DOI 10.1136/bmj.320.7251.1708.
Miscarriage risk for asymptomatic women after a normal first-trimester prenatal visit. (opens source in a new tab)
Tong S, Kaur A, Walker SP, Bryant V, et al.. Obstetrics and gynecology. 2008 Mar. DOI 10.1097/aog.0b013e318163747c.
Cited on: Miscarriage Risk Calculator | Week and day odds, Pregnancy Announcement Risk-by-Date Calculator
NVSS – Fetal Deaths (opens source in a new tab)
Cited on: Chance of Live Birth Calculator, Live Birth and Chromosome Risk Calculator
Obstetric Care Consensus #10: Management of Stillbirth: (Replaces Practice Bulletin Number 102, March 2009). (opens source in a new tab)
American College of Obstetricians and Gynecologists, Society for Maternal-Fetal Medicine in collaboration with, Metz TD, Berry RS, et al.. American journal of obstetrics and gynecology. 2020 Mar. DOI 10.1016/j.ajog.2020.01.017.
Cited on: Chance of Live Birth Calculator
Overview of ectopic pregnancy diagnosis, management, and innovation. (opens source in a new tab)
Mullany K, Minneci M, Monjazeb R, C Coiado O. Women's health (London, England). 2023 Jan-Dec. DOI 10.1177/17455057231160349.
Perinatal Outcomes in Women With Subchorionic Hematoma (opens source in a new tab)
Obstetrics & Gynecology. 2011. DOI 10.1097/aog.0b013e31821568de.
Cited on: Subchorionic Hematoma Risk Calculator by Week and Size
Predicting first-trimester spontaneous abortion. Ratio of mean sac diameter to crown-rump length compared to embryonic heart rate. (opens source in a new tab)
Tadmor OP, Achiron R, Rabinowiz R, Aboulafia Y, et al.. The Journal of reproductive medicine. 1994 Jun. PMID 7932400.
Cited on: Chance of Live Birth Calculator
Recurrent miscarriage: Are three miscarriages one too many? Analysis of a Scottish population-based database of 151,021 pregnancies. (opens source in a new tab)
Bhattacharya S, Townend J. European journal of obstetrics, gynecology, and reproductive biology. 2010 May. DOI 10.1016/j.ejogrb.2010.02.015.
Cited on: Chance of Live Birth Calculator, Live Birth and Chromosome Risk Calculator, Miscarriage Risk Calculator | Week and day odds
Risks of repeated miscarriage. (opens source in a new tab)
George L, Granath F, Johansson AL, Olander B, et al.. Paediatric and perinatal epidemiology. 2006 Mar. DOI 10.1111/j.1365-3016.2006.00703.x.
Cited on: Chance of Live Birth Calculator, Live Birth and Chromosome Risk Calculator, Miscarriage Risk Calculator | Week and day odds
Role of maternal age and pregnancy history in risk of miscarriage: prospective register based study. (opens source in a new tab)
Magnus MC, Wilcox AJ, Morken NH, Weinberg CR, et al.. BMJ (Clinical research ed.). 2019 Mar 20. DOI 10.1136/bmj.l869.
Cited on: Fertility Calculator by Age
Stillbirth (opens source in a new tab)
Cited on: Stillbirth Risk Calculator
Subchorionic Hematoma: Correlation of Grading Techniques With First-Trimester Pregnancy Outcome. (opens source in a new tab)
Heller HT, Asch EA, Durfee SM, Goldenson RP, et al.. Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine. 2018 Jul. DOI 10.1002/jum.14524.
Cited on: Subchorionic Hematoma Risk Calculator by Week and Size
Vanishing Twin Syndrome – StatPearls – NCBI Bookshelf (opens source in a new tab)
Cited on: Vanishing Twin Probability Calculator (by Week and Twin Type)
Prenatal Screening, Genetics & Inherited Traits (26)
[False positive non-invasive prenatal testing results due to vanishing twins]. (opens source in a new tab)
Yu T, Li S, Zhao W, Yu D. Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics. 2019 Apr 10. DOI 10.3760/cma.j.issn.1003-9406.2019.04.009.
Cited on: Vanishing Twin NIPT Timing Calculator
Age Specific Risk For Trisomies 13, 18 and 21 (opens source in a new tab)
Amniocentesis (opens source in a new tab)
Cited on: CVS or Amniocentesis After NIPT: Risk and Diagnostic-Yield Calculator, Live Birth and Chromosome Risk Calculator, Prenatal Testing Timeline and Results-Date Calculator
Amniocentesis (opens source in a new tab)
Chorionic villus sampling (opens source in a new tab)
Combining the use of a fetal fraction-based risk algorithm and probability of an informative redraw in noninvasive prenatal testing for fetal aneuploidy. (opens source in a new tab)
Benn P, Martin K, McKanna T, Valenti E, et al.. Journal of genetic counseling. 2020 Oct. DOI 10.1002/jgc4.1208.
Current ACOG Guidance on Non-Invasive Prenatal Testing (opens source in a new tab)
Cited on: Prenatal Testing Timeline and Results-Date Calculator
Fetal Medicine Foundation course notes on nuchal translucency assessment (opens source in a new tab)
courses.fetalmedicine.com.
Cited on: Nuchal Translucency Calculator | NT Percentile & NT From CRL
Genotype-phenotype associations and human eye color. (opens source in a new tab)
White D, Rabago-Smith M. Journal of human genetics. 2011 Jan. DOI 10.1038/jhg.2010.126.
Cited on: Baby Eye Color Calculator
Increased Nuchal Translucency Measurement (opens source in a new tab)
www.portsmouth.gov.uk.
Cited on: Nuchal Translucency Calculator | NT Percentile & NT From CRL
Is eye color determined by genetics?: MedlinePlus Genetics (opens source in a new tab)
medlineplus.gov.
Cited on: Baby Eye Color Calculator
Microarrays and Next-Generation Sequencing Technology The Use of Advanced Genetic Diagnostic Tools in Obstetrics and Gynecology (opens source in a new tab)
Cited on: CVS or Amniocentesis After NIPT: Risk and Diagnostic-Yield Calculator
NIPT Predictive Value Calculator (opens source in a new tab)
Cited on: CVS or Amniocentesis After NIPT: Risk and Diagnostic-Yield Calculator, NIPT PPV and Residual Risk Calculator
Nuchal translucency assessment (opens source in a new tab)
The Fetal Medicine Foundation.
Cited on: Nuchal Translucency Calculator | NT Percentile & NT From CRL
Performance of non-invasive prenatal testing in vanishing-twin and multiple pregnancies: results of TRIDENT-2 study. (opens source in a new tab)
van Eekhout JCA, Bax CJ, Schuurman LVP, Becking EC, et al.. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 2025 Dec. DOI 10.1002/uog.70015.
Cited on: Vanishing Twin NIPT Timing Calculator
Prenatal Genetic Screening Tests (opens source in a new tab)
www.acog.org.
Cited on: Pregnancy Screening Schedule by Gestational Age, Prenatal Testing Timeline and Results-Date Calculator
Prenatal Genetic Testing Timing (opens source in a new tab)
Cited on: IUI Due Date Calculator
Residual risk for clinically significant copy number variants in low-risk pregnancies, following exclusion of noninvasive prenatal screening-detectable findings. (opens source in a new tab)
Maya I, Salzer Sheelo L, Brabbing-Goldstein D, Matar R, et al.. American journal of obstetrics and gynecology. 2022 Apr. DOI 10.1016/j.ajog.2021.11.016.
Cited on: CVS or Amniocentesis After NIPT: Risk and Diagnostic-Yield Calculator
Results | Women’s Health (opens source in a new tab)
Cited on: Prenatal Testing Timeline and Results-Date Calculator
Risk of miscarriage following amniocentesis or chorionic villus sampling: systematic review of literature and updated meta-analysis. (opens source in a new tab)
Salomon LJ, Sotiriadis A, Wulff CB, Odibo A, et al.. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 2019 Oct. DOI 10.1002/uog.20353.
Cited on: CVS or Amniocentesis After NIPT: Risk and Diagnostic-Yield Calculator, Live Birth and Chromosome Risk Calculator
Screening for Fetal Chromosomal Abnormalities (opens source in a new tab)
Cited on: Live Birth and Chromosome Risk Calculator, NIPT PPV and Residual Risk Calculator, NIPT Redraw Success and Best Date Calculator
Should vanishing twin pregnancies be systematically excluded from cell-free fetal DNA testing? (opens source in a new tab)
Balaguer N, Mateu-Brull E, Serra V, Simón C, et al.. Prenatal diagnosis. 2021 Sep. DOI 10.1002/pd.5817.
Cited on: Vanishing Twin NIPT Timing Calculator
SMFM Consult Series #74: Cell-free DNA screening for aneuploidies (opens source in a new tab)
Cited on: CVS or Amniocentesis After NIPT: Risk and Diagnostic-Yield Calculator, Live Birth and Chromosome Risk Calculator, NIPT PPV and Residual Risk Calculator
What Color Will My Baby's Eyes Be? – HealthyChildren.org (opens source in a new tab)
www.healthychildren.org.
Cited on: Baby Eye Color Calculator
What colour are your eyes? Teaching the genetics of eye colour & colour vision. Edridge Green Lecture RCOphth Annual Congress Glasgow May 2019. (opens source in a new tab)
Mackey DA. Eye (London, England). 2022 Apr. DOI 10.1038/s41433-021-01749-x.
Cited on: Baby Eye Color Calculator
What Nuchal Translucency Threshold Is Best for Identifying Atypical Chromosome Abnormalities? (opens source in a new tab)
Cited on: Nuchal Translucency Calculator | NT Percentile & NT From CRL
Maternal Health, Placenta & Pregnancy Complications (25)
2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum. (opens source in a new tab)
Alexander EK, Pearce EN, Brent GA, Brown RS, et al.. Thyroid : official journal of the American Thyroid Association. 2017 Mar. DOI 10.1089/thy.2016.0457.
Cited on: TSH Levels in Pregnancy Interpreter & Levothyroxine Dosage Chart
A sonographic endometrial thickness <7 mm in women undergoing in vitro fertilization increases the risk of placenta accreta spectrum. (opens source in a new tab)
Lai S, Zhang L, Luo Y, Gu Z, et al.. American journal of obstetrics and gynecology. 2024 Nov. DOI 10.1016/j.ajog.2024.02.301.
ACOG SMFM Obstetric Care Consensus #7: Placenta Accreta Spectrum – SMFM Publications and Clinical Guidelines (opens source in a new tab)
Birth after Previous Caesarean Birth (Green-top Guideline No. 45) | RCOG (opens source in a new tab)
www.rcog.org.uk.
Cited on: VBAC Calculator | Probability of Successful Vaginal Birth After Caesarean
Development of a nomogram for prediction of vaginal birth after cesarean delivery. (opens source in a new tab)
Grobman WA, Lai Y, Landon MB, Spong CY, et al.. Obstetrics and gynecology. 2007 Apr. DOI 10.1097/01.aog.0000259312.36053.02.
Cited on: VBAC Calculator | Probability of Successful Vaginal Birth After Caesarean
FIGO Consensus Guidelines – Placenta Accreta Spectrum Disorders | Figo (opens source in a new tab)
Gestational Diabetes (opens source in a new tab)
www.acog.org.
Hypothyroidism during pregnancy: Clinical manifestations, diagnosis, and treatment (opens source in a new tab)
www.uptodate.com.
Cited on: TSH Levels in Pregnancy Interpreter & Levothyroxine Dosage Chart
Inducing labour – NHS (opens source in a new tab)
www.nhs.uk.
Cited on: Bishop Score Calculator | Readiness for Labour and Induction
ISUOG Practice Guidelines (updated): use of Doppler velocimetry in obstetrics. – SORA (opens source in a new tab)
Labor Induction (opens source in a new tab)
www.acog.org.
Cited on: Bishop Score Calculator | Readiness for Labour and Induction
Occupational factors and risk of preterm birth in nurses (opens source in a new tab)
Lawson CC, Whelan EA, Hibert EN, Grajewski B, et al.. American Journal of Obstetrics and Gynecology. 2009 Jan. DOI 10.1016/j.ajog.2008.08.006.
Established Research Library reference.
Overview | Inducing labour | Guidance (opens source in a new tab)
www.nice.org.uk.
Cited on: Bishop Score Calculator | Readiness for Labour and Induction
PELVIC SCORING FOR ELECTIVE INDUCTION. (opens source in a new tab)
BISHOP EH. Obstetrics and gynecology. 1964 Aug. PMID 14199536.
Cited on: Bishop Score Calculator | Readiness for Labour and Induction
Placenta Accreta Spectrum (opens source in a new tab)
Placenta praevia (low-lying placenta) | CUH (opens source in a new tab)
www.cuh.nhs.uk.
Cited on: Placenta Accreta Spectrum (PAS) Risk Calculator, Placenta Previa and Low-Lying Placenta Resolution Calculator (by Week and mm)
Placenta Praevia and Placenta Accreta: Diagnosis and Management (Green-top Guideline No. 27a) (opens source in a new tab)
Royal College of Obstetricians and Gynaecologists.
Cited on: Placenta Previa and Low-Lying Placenta Resolution Calculator (by Week and mm)
Placenta Praevia and Placenta Accreta: Diagnosis and Management (Green-top Guideline No. 27a) | RCOG (opens source in a new tab)
RCOG obstetric thromboprophylaxis risk assessment tool (opens source in a new tab)
NICE / Royal College of Obstetricians and Gynaecologists.
Cited on: Pregnancy VTE Risk Score Calculator | Venous Thromboembolism
Reducing the Risk of Thrombosis and Embolism during Pregnancy and the Puerperium (Green-top Guideline No. 37a) | RCOG (opens source in a new tab)
www.rcog.org.uk.
Cited on: Pregnancy VTE Risk Score Calculator | Venous Thromboembolism
Reducing the Risk of Venous Thromboembolism during Pregnancy and the Puerperium (Green-top Guideline No. 37a) (opens source in a new tab)
Royal College of Obstetricians and Gynaecologists.
Cited on: Pregnancy VTE Risk Score Calculator | Venous Thromboembolism
RETIRED: Management of Thyroid Dysfunction during Pregnancy and Postpartum | Endocrine Society (opens source in a new tab)
www.endocrine.org.
Cited on: TSH Levels in Pregnancy Interpreter & Levothyroxine Dosage Chart
Thromboembolism in Pregnancy (opens source in a new tab)
www.acog.org.
Cited on: Pregnancy VTE Risk Score Calculator | Venous Thromboembolism
Vaginal Birth After Cesarean Delivery (VBAC) (opens source in a new tab)
www.acog.org.
Cited on: VBAC Calculator | Probability of Successful Vaginal Birth After Caesarean
Venous thromboembolism (VTE) prophylaxis in pregnancy and the puerperium (opens source in a new tab)
Cited on: Pregnancy VTE Risk Score Calculator | Venous Thromboembolism
Male Fertility & Paternity (10)
Clarifying the Relationship Between Total Motile Sperm Count and IUI Success (opens source in a new tab)
Consistent age-dependent declines in human semen quality: a systematic review and meta-analysis. (opens source in a new tab)
Johnson SL, Dunleavy J, Gemmell NJ, Nakagawa S. Ageing research reviews. 2015 Jan. DOI 10.1016/j.arr.2014.10.007.
Cited on: Advanced Pregnancy Chance Calculator, One-Time Pregnancy Calculator: Percent Chance from a Single Encounter, Pregnancy Chance Calculator
Diagnosis and Treatment of Infertility in Men: AUA/ASRM Guideline – American Urological Association (opens source in a new tab)
www.auanet.org.
Cited on: Semen Analysis & TMSC Interpreter, Sperm DNA Fragmentation Risk Calculator
For Patients – SCSA (opens source in a new tab)
scsalab.com.
Cited on: Sperm DNA Fragmentation Risk Calculator
Review of Vasectomy Complications and Safety Concerns (opens source in a new tab)
The World Journal of Men's Health. 2021. DOI 10.5534/wjmh.200073.
Cited on: Vasectomy Failure Risk Calculator
Sperm lifecycle and life span | Clearblue (opens source in a new tab)
The Sixth Edition of the WHO Manual for Human Semen Analysis: A Critical Review and SWOT Analysis. (opens source in a new tab)
Boitrelle F, Shah R, Saleh R, Henkel R, et al.. Life (Basel, Switzerland). 2021 Dec 9. DOI 10.3390/life11121368.
Cited on: Sperm DNA Fragmentation Risk Calculator
Vasectomy: AUA Guideline (opens source in a new tab)
American Urological Association.
Cited on: Vasectomy Failure Risk Calculator
Vasectomy: AUA Guideline (2026) – American Urological Association (opens source in a new tab)
Cited on: Vasectomy Failure Risk Calculator
WHO laboratory manual for the examination and processing of human semen, 6th ed (opens source in a new tab)
www.who.int.
Cited on: Semen Analysis & TMSC Interpreter
Labour, Birth, Breastfeeding & Postpartum (15)
Appendix G: Lactational Amenorrhea Method (opens source in a new tab)
Cited on: Breastfeeding (LAM) Eligibility & Risk Calculator, Postpartum Ovulation & Fertility Calculator
C-section: What to expect (opens source in a new tab)
Cited on: C-Section Recovery Timeline Calculator: Personalized Healing Schedule
Caesarean section – Recovery – NHS (opens source in a new tab)
www.nhs.uk.
Cited on: C-Section Recovery Timeline Calculator: Personalized Healing Schedule
Cesarean Birth (opens source in a new tab)
www.acog.org.
Cited on: C-Section Recovery Timeline Calculator: Personalized Healing Schedule
Characteristics and determinants of postpartum ovarian function in women in the United States. (opens source in a new tab)
Campbell OM, Gray RH. American journal of obstetrics and gynecology. 1993 Jul. DOI 10.1016/0002-9378(93)90131-2.
Considering a caesarean birth | RCOG (opens source in a new tab)
www.rcog.org.uk.
Cited on: C-Section Recovery Timeline Calculator: Personalized Healing Schedule
Contraceptive efficacy of lactational amenorrhoea. (opens source in a new tab)
Kennedy KI, Visness CM. Lancet (London, England). 1992 Jan 25. DOI 10.1016/0140-6736(92)90018-x.
Family Planning: A Global Handbook for Providers — LAM (opens source in a new tab)
fphandbook.org.
How To Be Reasonably Certain that a Patient Is Not Pregnant (opens source in a new tab)
Lactation and birth spacing in highland new guinea (opens source in a new tab)
Physiological mechanisms underlying lactational amenorrhea. (opens source in a new tab)
McNeilly AS, Tay CC, Glasier A. Annals of the New York Academy of Sciences. 1994 Feb 18. DOI 10.1111/j.1749-6632.1994.tb30394.x.
Cited on: Postpartum Period Calculator: When Will My Fertility Return?
The Current Status of Postpartum Menstrual Resumption Delay and Associated Risk Factors in Japanese Women: An Adjunct Study of the Japan Environment and Children's Study. (opens source in a new tab)
Samejima A, Motoki N, Haga A, Tokutake C, et al.. Yonago acta medica. 2024 Aug. DOI 10.33160/yam.2024.08.005.
The resumption of ovulation and menstruation in a well-nourished population of women breastfeeding for an extended period of time (opens source in a new tab)
The World Health Organization multinational study of breast-feeding and lactational amenorrhea. I. Description of infant feeding patterns and of the return of menses (opens source in a new tab)
The World Health Organization multinational study of breast-feeding and lactational amenorrhea. II. Factors associated with the length of amenorrhea (opens source in a new tab)
General Population, Lifestyle & Demographic Evidence (2)
Infant Mortality in the United States: Provisional Data From the 2022 Period Linked Birth/Infant Death File (opens source in a new tab)
Cited on: Chance of Live Birth Calculator, Live Birth and Chromosome Risk Calculator
Sleep, sleepiness, and alcohol use. (opens source in a new tab)
Roehrs T, Roth T. Alcohol research & health : the journal of the National Institute on Alcohol Abuse and Alcoholism. 2001. PMID 11584549.
Cited on: BBT Time Adjustment Calculator
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