Trying to figure out your chances of miscarrying? Sadly, you are going to have a hard time finding good information.
Many websites claim to tell you your risk of miscarriage, citing statistics that look like these:

But problems abound with their numbers.
Problem 1: These sites rarely provide their sources, so you cannot tell whether their information is reliable.
Problem 2: These sites do not breakdown miscarriage risk by other known risk factors, like the mother’s age.
Problem 3: Nearly all these sites derive their statistics from just two small studies, one which tracked 222 women from conception through just the first 6 weeks of pregnancy, and another which tracked 697 pregnancies, but only after a fetal heartbeat had been detected–a key point, because heartbeat detection dramatically lowers the chances of a miscarriage.
The lack of good information frustrated me when I was pregnant, and I bet it frustrates you too. So I have compiled a summary of the best research on risk of miscarriage. Where possible, I break down the risk by…
- pregnancy week
- before a heartbeat has been detected
- after a heartbeat has been detected
- fetal heart rate
- mother’s age
- father’s age
- number of prior miscarriages
Edit: I also have a new post on how morning sickness signals a lower risk.
Continue reading “Lies, Damned Lies, and Miscarriage Statistics”