This calculator estimates the chance of miscarriage from the entered gestational age up to 20 weeks. It is a statistical estimate and does not diagnose miscarriage or confirm viability.
Inputs used
- Maternal age (years)
- Gestational age (week and day)
- Ultrasound status and whether a fetal heartbeat was seen
- Optional fetal heart rate (bpm) when heartbeat is marked as seen
- Previous miscarriages and previous live births
- Bleeding (yes/no)
- Height and weight to estimate BMI (optional). Imperial and metric supported.
How the estimate is calculated
Baseline risk comes from gestational age. If a heartbeat is detected, a lower baseline curve is used. Risk is then adjusted using odds ratios for maternal age, pregnancy history, BMI, bleeding, and (when applicable) fetal heart rate. The final risk is clamped between 0.1% and 99%. Chance of continuing = 100% minus risk.
Guardrails
- Gestational age 20 weeks or more: loss after 20 weeks is classified as stillbirth.
- Ultrasound yes, week ≥11, heartbeat no: specialist message is shown instead of a percentage.
Sources: Nybo Andersen et al. (BMJ 2000); ACOG Practice Bulletin; NICE NG126; StatPearls Early Pregnancy Loss; peer-reviewed studies on recurrent loss, BMI, and fetal heart rate.
Medical disclaimer
The information and calculators on this site are for education only. They cannot diagnose, predict your outcome, or replace advice from a licensed healthcare professional. Always talk with your doctor or midwife about your health or pregnancy. In a medical emergency, call 911 (US) or your local emergency number.