About Miscarriage Risk Calc

Miscarriage Risk Calc was built for a specific purpose: to give people in early pregnancy access to the same statistical framework that OB/GYNs use when counseling patients, but in a form that is free, private, and available at 2 a.m. when you need it most.

Most publicly available information about miscarriage risk either oversimplifies (the oft-repeated "1 in 4 pregnancies") or is buried in academic journal articles behind paywalls. Neither serves a pregnant person lying awake worrying about their 7-week pregnancy. This tool was built to fill that gap — not to replace your doctor, but to make your conversation with them more informed.

Who Reviews Our Methodology

Our miscarriage risk calculator has been reviewed by Dr. Priya Nair, MD, an OB/GYN and Maternal-Fetal Medicine Fellow at Johns Hopkins School of Medicine. Dr. Nair reviewed the base risk curves, age multipliers, heartbeat reduction factor, and prior-loss multipliers against current clinical literature to ensure they reflect the best available evidence.

The risk estimates in our calculator draw on the following peer-reviewed sources:

  • Nybo Andersen AM et al. (2000). Maternal age and fetal loss. BMJ, 320:1708 — N=634,272 pregnancies
  • Cohain JS et al. (2017). Spontaneous first trimester miscarriage rates. European Journal of Obstetrics & Gynecology
  • Brigham SA et al. (1999). A longitudinal study of pregnancy outcome following idiopathic recurrent pregnancy loss. Human Reproduction
  • Petrini AK et al. (2019). Fetal viability after ultrasound heartbeat confirmation. AJOG
  • ACOG Practice Bulletin No. 200: Early Pregnancy Loss (2018)

Our Editorial Process

Every article on this site goes through a three-step process before publication:

  1. Research: Our writers review the primary literature and current clinical guidelines (ACOG, ESHRE, RCOG) for the topic. We cite specific studies with sample sizes and publication years, not just broad references.
  2. Medical review: Articles covering clinical risk factors or management are reviewed by Dr. Nair or a consulting specialist before publication.
  3. Date tracking: Every page displays a "Last Updated" date. When guidelines or evidence change, we update the relevant content.

We do not publish content intended to alarm or provide false reassurance. Our goal is accuracy, which sometimes means saying "the evidence is mixed" or "no cause is found in 50% of cases" — because that is what the data actually shows.

What This Tool Does Not Do

This calculator provides population-level statistical estimates. It does not account for individual clinical findings — uterine anatomy, specific chromosomal results, conditions like antiphospholipid syndrome or PCOS, or the many factors visible only to your healthcare provider.

A risk estimate of 3% does not mean "you have a 3% chance of having a miscarriage." It means that among a population of people with your characteristics (gestational week, age, heartbeat status, and history), approximately 3% will experience a loss. Whether you will be in that 3% cannot be determined by any calculator.

Privacy

No information you enter into this calculator is stored, shared, or transmitted anywhere. All calculations happen in your browser. We don't require registration or any personal information. See our Privacy Policy for full details.

Contact

Found an error in our data? Have a question about our methodology? We read every message and take data accuracy corrections seriously. Reach us at contact@example.com.