Risk of Miscarriage Calculator

Reviewed By Dr. Sarah Bennett, MD, OB/GYN — Medical Review Board

Understand the statistical probability of pregnancy continuation based on maternal age and gestational weeks with our risk of miscarriage calculator.

Risk of Miscarriage Calculator

Please enter a valid age (15-55).

Please enter valid weeks (3-42).

*This result is based on population statistics and is not a medical diagnosis. Every pregnancy is unique.

Calculation Logic:

Waiting for input…

Risk of Miscarriage Calculator Formula

While miscarriage risk is biologically complex, statistical models often use regression based on maternal age and gestational age. The simplified logic used in this risk of miscarriage calculator approximates data from large-scale population studies.

Risk % ≈ Base_Age_Risk × (Decay_Factor ^ (Weeks – 3))

Formula Source & Reference Data: National Institutes of Health (NIH) – Risk of Miscarriage Analysis.

Variables

• Maternal Age (A): The age of the mother at conception. Risk tends to increase significantly after age 35 due to chromosomal factors.
• Weeks Pregnant (W): Gestational age measured from the last menstrual period. Risk decreases dramatically after the heartbeat is detected (approx. week 6-8) and continues to drop entering the second trimester.

Related Calculators

• Pregnancy Due Date Calculator
• Conception Date Calculator
• HCG Levels Calculator
• Pregnancy Weight Gain Calculator

What is a Risk of Miscarriage Calculator?

A risk of miscarriage calculator is a digital tool designed to provide expectant parents with data-driven estimates regarding the likelihood of pregnancy continuation. It utilizes historical medical statistics to project the probability of pregnancy loss based on specific input variables, primarily the mother’s age and the current gestational week.

It is important to understand that these calculators provide statistical probabilities based on groups of people, not individual medical predictions. Factors such as medical history, lifestyle, and genetic screenings play a crucial role that a simple online calculator cannot fully capture. Always consult with your healthcare provider for personal medical advice.

How to Calculate Risk of Miscarriage (Example)

Here is an example of how the calculation works for a 30-year-old woman at 8 weeks pregnant:

1. Determine Base Risk: At age 30, the baseline risk at conception is approximately 15-20%.
2. Apply Week Factor: By week 8, the risk drops significantly because the pregnancy has progressed past the chemical pregnancy stage.
3. Calculate Decay: The statistical model reduces the risk by roughly 10-15% for every successful week passed.
4. Result: At 8 weeks, the remaining risk might be calculated around 4-5%, meaning there is a ~95% probability of the pregnancy continuing.

Frequently Asked Questions (FAQ)

When does the risk of miscarriage drop the most?

The risk drops significantly after a fetal heartbeat is detected, usually around 6 to 8 weeks of gestation. It drops again dramatically upon entering the second trimester (week 13).

Does maternal age affect miscarriage risk?

Yes. Maternal age is the strongest independent predictor of pregnancy loss risk, primarily due to the increased rate of chromosomal abnormalities in eggs as women age.

How accurate is this risk of miscarriage calculator?

This calculator provides estimates based on general population data. It cannot account for individual health conditions like PCOS, thyroid issues, or history of recurrent loss.

What is the “safe zone” in pregnancy?

While no time is guaranteed 100% risk-free, the risk falls to less than 1% for most women after 14 weeks of pregnancy.