Use this tool to interpret a progesterone test in early pregnancy. Enter your value, unit, and gestational age or days past ovulation to see a level band and next steps. Progesterone alone cannot diagnose viability, so follow up with your clinician for concerning symptoms or unclear results.
* This comparison applies to pregnancy; it cannot confirm pregnancy or show whether it is developing normally. Before 5 weeks, it uses a broad first-trimester lab range. Weekly ranges come from pregnancies without bleeding or progesterone treatment. Use your lab’s range and your clinician’s advice, especially with symptoms or supplements.
How to use this calculator
- Enter your progesterone result and choose the unit (ng/mL or nmol/L). The tool can convert units.
- Enter gestational age in weeks and days, or days past ovulation if you are tracking DPO.
- Tell the tool if you are on progesterone support and the form used (vaginal, oral, or IM) if shown.
- Optional: add symptoms such as bleeding or cramping for relevant care guidance.
- Read the level band and comparison range. If your clinician recommends repeat testing in 48–72 hours, the calculator gives those dates.
Educational only, not medical advice. Exogenous progesterone can inflate serum levels. Seek care for heavy bleeding, severe pain, dizziness, or fainting.
Methodology & sources
How this estimate works
- Pregnancy stage: gestational age is entered directly or calculated as DPO plus 14 days. For example, 14 DPO and 4 weeks 0 days use the same range.
- Weeks 5–12: ranges are the 2.5th to 97.5th percentiles for each completed week in Ku et al., Table 2. These describe the middle 95% of values in a study of 590 low-risk singleton pregnancies that remained viable at 16 weeks. Participants with bleeding or progesterone treatment were excluded. A week’s range covers its days 0–6.
- Before 5 weeks: the comparison is the broad Mayo Clinic Laboratories first-trimester range of 11–44 ng/mL, not a week-specific range. It applies to established pregnancy; a progesterone result cannot confirm pregnancy.
- Level bands: below, within or above refers only to the displayed comparison range. Calculations use the source values before display rounding. The weekly study ranges are separate groups, not the expected rise in one person’s progesterone.
- Follow-up dates: the calculator shows 2–3 calendar days from today for a clinician-advised 48–72-hour repeat. Whether progesterone, hCG or ultrasound is appropriate depends on your circumstances. In pregnancy of unknown location, NICE advises against using progesterone alongside serial hCG to diagnose viability or an ectopic pregnancy.
Units and conversion
Inputs accept either unit. The converter uses 1 ng/mL = 3.18 nmol/L (standard SI factor used across clinical labs).
Supplementation effects
- Vaginal: serum levels may not reflect uterine tissue exposure in the same way as intramuscular dosing (Cicinelli et al., 2000).
- Oral: variable serum due to first-pass metabolism; numbers can appear lower.
- IM injection: produces high serum peaks; a sample drawn soon after a dose may read high without indicating excessive uterine exposure .
- Timing: we ask “hours since last dose” to remind that near-dose blood draws can skew interpretation.
Symptoms and safety
Bleeding or significant pain should prompt clinical advice regardless of a single progesterone value. Early follow-up is recommended when symptoms change (NICE NG126).
Limitations
- Reference intervals vary by lab, assay, and population; using the same lab reduces variance.
- Progesterone alone cannot diagnose a healthy or non-viable pregnancy; use with hCG trend and ultrasound when appropriate (ACOG).
- Supplement route and timing alter serum levels without directly reflecting uterine exposure.
- A value inside the range does not confirm a healthy pregnancy; a value outside it does not diagnose a loss. Treatment targets may differ from these comparison ranges.
- Ku et al., Scientific Reports, 2021: Gestational age-specific normative values and determinants of serum progesterone through the first trimester of pregnancy — Table 2, weekly percentile ranges at 5–12 weeks; cross-sectional data, not individual progesterone trends.
- Mayo Clinic Laboratories: Progesterone, Serum (PGSN) — first-trimester laboratory reference and SI conversion.
- NICE NG126: Ectopic pregnancy and miscarriage — assessment and follow-up pathways; emphasis on trends and ultrasound confirmation.
- ACOG Practice Bulletin: Early Pregnancy Loss — evaluation with serial hCG and ultrasound; cautions interpreting single labs.
- Cicinelli et al., Hum Reprod, 2000 — uterine tissue and serum exposure after vaginal versus intramuscular progesterone.
Frequently asked questions
What does progesterone do in early pregnancy?
Progesterone supports the uterine lining and helps maintain early pregnancy. Levels vary by person and timing.
How do I convert ng/mL to nmol/L?
The calculator converts units for you. As a guide, 1 ng/mL is about 3.18 nmol/L.
Do supplements affect the result?
Yes. Vaginal, oral, or intramuscular progesterone can raise measured levels. Results include a caution if you are on support.
Should I repeat the test?
Follow your clinician’s advice about whether to repeat progesterone or have hCG tests or ultrasound. If they recommend a repeat in 48–72 hours, the calculator provides those dates.
Can a low level predict miscarriage?
Low levels can be associated with risk, but they are not diagnostic on their own. Interpretation is strongest with ultrasound and hCG trends.
When should I seek urgent care?
Seek urgent care for heavy bleeding, severe pain, shoulder pain, dizziness, or fainting.
Support if you have experienced a loss
Reading about miscarriage, stillbirth, or infant loss can be difficult. If you have experienced a loss, you do not have to use this calculator or read the statistics. You may find it more helpful to talk with your care team or a support organization.
In the United States, groups such as:
offer information and bereavement support. If you are elsewhere, your local health service or a pregnancy and baby loss charity may be able to guide you to support in your region.