Quick Calculators

Pregnancy Probability Calculator

Track how the statistical probability of a successful pregnancy increases every single day during your first trimester.

PROBABILITY OF NOT MISCARRYING
85.0%

At 6 weeks and 0 days, your pregnancy has a 85.0% chance of continuing successfully!

Statistical risk of miscarriage: 15.0%
Important Disclaimer: This calculator provides broad statistical averages based on clinical population studies. It does NOT diagnose or predict the outcome of your individual pregnancy. Many personal health factors influence pregnancy. If you are experiencing bleeding, cramping, or are concerned about your pregnancy, contact your healthcare provider immediately.

Last updated: July 2026

Understanding Pregnancy Probability

The first trimester of pregnancy can be an incredibly anxious time. It is common for expecting parents to worry about the health and viability of their pregnancy before they can feel the baby move. Our Miscarriage Risk Calculator (also known as a Pregnancy Probability Calculator) is designed to provide reassurance by showing you the statistical likelihood that your pregnancy will continue successfully.

The Odds Are in Your Favor

When searching online, it's easy to find frightening statistics about pregnancy loss. However, it is crucial to flip the perspective: as your pregnancy progresses, the odds of a successful, healthy outcome increase drastically every single day.

  • At 4 Weeks: You have just missed your period. The probability of the pregnancy continuing successfully is already around 75%.
  • At 8 Weeks: You are halfway through the first trimester. The probability of success has jumped to roughly 95%.
  • At 12 Weeks: You are nearing the end of the first trimester. The probability of success is now nearly 99%.

Why Does the Risk Drop?

Most early pregnancy loss occurs because the embryo has a chromosomal abnormality that prevents it from developing properly. If an embryo survives those crucial early weeks and develops a strong heartbeat, it usually indicates that the chromosomes are healthy and normal, drastically lowering the risk of miscarriage moving forward.

How Maternal Age Factors In

Age is one of the biggest drivers of individual risk, mainly because of the rising chance of chromosomal abnormalities in eggs as women get older. Based on large population studies, overall pregnancy risk runs roughly 10-11% under age 35, climbs to about 17% for ages 35-39, around 33% for ages 40-44, and roughly 53% or higher from age 45 onward. That's why this calculator asks for your age bracket separately from your gestational age — both move the number meaningfully.

How to Use This Tool

Enter your exact gestational age (in weeks and days) and select your age bracket. We highly recommend focusing on the large, green Probability of Success number rather than the risk percentage. Watching that success number climb higher and higher each day can be a great source of comfort during the long wait for your next ultrasound.

This tool reflects broad population statistics, not a diagnosis or prediction for your specific pregnancy. If you're experiencing bleeding, cramping, or have any concerns, contact your healthcare provider.

Frequently Asked Questions

The risk of miscarriage is highest in the first few weeks following conception. However, once a fetal heartbeat is detected on an ultrasound (usually around 6 to 7 weeks), the risk drops significantly. By the end of the first trimester (week 13), the statistical risk of miscarriage drops to about 1%.
Yes, maternal age is one of the strongest statistical factors. Large population studies put overall pregnancy risk at roughly 10-11% for women under 35, about 17% for ages 35-39, around 33% for ages 40-44, and roughly 53% or higher for women 45 and older.
No. The vast majority of first-trimester miscarriages (up to 80%) are caused by random chromosomal abnormalities that occur during fertilization. They are not caused by exercise, stress, working, or anything the mother did.
Yes. Research shows women 45+ face roughly five times the miscarriage risk of women under 35 — notably higher than the 40-44 age group, which is why this calculator treats them as separate categories.
Not much. A single prior loss carries a recurrence risk of roughly 14-20%, close to the general baseline. It's typically two or more consecutive losses that prompts further medical evaluation.
No, it uses general population averages by week and age rather than your personal scan results. If you've already had an ultrasound with a confirmed heartbeat, your individual risk is likely lower than the population average shown here.
Contact your healthcare provider immediately. These statistics describe population averages and are not a substitute for medical evaluation of your symptoms.