Miscarriage Risk Calculator: Understanding Your Odds

Enter your age and week of pregnancy to see an estimated miscarriage risk. You can add optional factors for a more tailored result.

Miscarriage Risk Calculator

Next step

Calculate your estimated due date

Get an EDD from your last period or conception date and map week-by-week milestones.

Open Due Date Calculator

How to use this calculator

  1. Enter your age: type your age in years.
  2. Select your week: choose the current week of pregnancy.
  3. Optional advanced inputs: open Advanced options to add heartbeat status, prior miscarriages and births, and BMI via height and weight.
  4. See your estimate: press Calculate to view percent risk and the chance of continuing.

This tool is informational only. Use with clinical judgment.

Last updated: September 2025

A screenshot of the Miscarriage Risk Calculator with example age and week selected.

The Science Behind Miscarriage Risk

It’s important to know that miscarriage is not anyone’s fault. It is most often a result of chromosomal abnormalities in the embryo that make a healthy pregnancy impossible. The statistical risk is influenced primarily by two well-documented factors, which our calculator uses to generate its estimate.

1. Maternal Age (The Primary Factor): The single most significant factor influencing miscarriage risk is the age of the mother. This is because the risk of chromosomal issues in an egg increases with age. Our calculator uses a baseline risk model established by large-scale studies.¹

2. Gestational Week (The Reassuring Timeline): The risk of miscarriage decreases significantly as a pregnancy progresses. The highest risk is very early on, often before a pregnancy is even confirmed. After a fetal heartbeat is detected (usually around 6-7 weeks), the chances of the pregnancy continuing increase dramatically each week.

Our calculator combines these two factors to provide a snapshot of the statistical risk at a specific point in time. It shows how the baseline risk associated with age is significantly reduced by each successful week of pregnancy.

A line chart showing risk decreasing over time for different age groups.

¹The data model is based on findings from a landmark study on fetal loss: Nybo Andersen, A. M., Wohlfahrt, J., Christens, P., Olsen, J., & Melbye, M. (2000). Maternal age and fetal loss: a population-based register-linkage study. BMJ, 320(7251), 1708–1712.

Frequently asked questions

What week has the highest miscarriage risk?

Risk is highest very early in pregnancy. Many losses occur before 12 weeks, especially in the first few weeks and around weeks 6 to 8. Risk declines as weeks progress.

Does a detected heartbeat lower risk?

Yes. After a fetal heartbeat is confirmed on ultrasound, the ongoing risk generally falls and keeps dropping toward the end of the first trimester.

Is this calculator a diagnosis?

No. It is a statistical tool for education only. It does not replace care from your clinician.

How does this calculator estimate risk?

It uses week of pregnancy and age as a baseline, then adjusts for heartbeat status, prior miscarriages, prior live births, and BMI from height and weight.

What is the difference between a miscarriage and a stillbirth?

A loss before 20 weeks is usually called a miscarriage. A loss at 20 weeks or later is usually called a stillbirth.

I am spotting. What should I do?

Some light spotting can occur in early pregnancy. If you have bleeding, cramps, or any concern, contact your clinician promptly.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult with a healthcare provider for any health concerns or before making any decisions related to your health or pregnancy.

Research studies we used

  1. Nybo Andersen AM, Wohlfahrt J, Christens P, Olsen J, Melbye M. Maternal age and fetal loss: population based register linkage study. BMJ. 2000;320:1708-1712. DOI | Article
  2. Avalos LA, Galindo C, Li DK. A systematic review to calculate background miscarriage rates using life table analysis. Birth Defects Res A. 2012;94(6):417-423. DOI | PubMed
  3. Tong S, Kaur A, Walker SP, Bryant V, Onwude JL, Permezel M. Miscarriage risk for asymptomatic women after a normal first-trimester prenatal visit. Obstet Gynecol. 2008;111(3):710-714. Journal | PubMed
  4. Magnus MC, Wilcox AJ, Morken NH, Weinberg CR, Håberg SE. Role of maternal age and pregnancy history in risk of miscarriage: prospective register based study. BMJ. 2019;364:l869. Article | PDF
  5. Maconochie N, Doyle P, Prior S, Simmons R. Risk factors for first trimester miscarriage: UK population-based case–control study. BJOG. 2007;114:170-186. DOI | PubMed
  6. Metwally M, Ong KJ, Ledger WL, Li TC. Does high body mass index increase the risk of miscarriage after spontaneous and assisted conception? A meta-analysis of the evidence. Fertil Steril. 2008;90(3):714-726. DOI | PubMed