The American Pregnancy Association states that in most healthy women who conceive naturally, the chances of having a miscarriage can range from 10% to 25%, averaging a 15% to 20% chance of miscarriage. In contrast, one 2003 study found that women who underwent IVF and got pregnant with a single child miscarried almost 22% of the time, a slightly elevated risk of miscarriage for women who use IVF and get pregnant with a single embryo.
What’s Behind the Elevated Risk?
It’s important to note that researchers do not believe that the reason for the increased risk of miscarriage necessarily relates to the IVF procedure itself. Rather it is more likely that the increased risk of miscarriage after in vitro fertilization (or another fertility treatment) has more to do with the underlying reasons for the fertility treatment. In other words, patients who have a need for in vitro fertilization may simply be in a higher risk category for miscarriage, regardless of the means of conception—unfair as that may be. Here are a few possible explanations.
Advanced Age
Women who undergo in vitro fertilization tend to be older than women who conceive naturally, and older maternal age is associated with a higher risk of miscarriage. For example, women between the ages of 35 and 45 have a 20% to 35% chance of miscarriage and women over age 45 can have up to a 50% chance of miscarriage.
Underlying Health Problem
Women who use IVF are more likely to have an underlying health condition that could possibly contribute to a higher risk of miscarriage.
Early Awareness
When a woman uses IVF, she generally pays very close attention to each cycle and finds out that she’s pregnant very early in the process. Women who conceive naturally, on the other hand, may not know they’re pregnant as early—especially if the pregnancy is unexpected. Because the risk of miscarriage is highest during the first few weeks of pregnancy, many women who conceive naturally may miscarry before they even realize they’re pregnant. This is often referred to as a chemical pregnancy.
Ovarian Stimulation
One 2004 study found that how much ovarian stimulation a woman receives while using assisted reproductive technology may play a role. Those researchers saw an association between higher ovarian stimulation and miscarriage risk. So, don’t be dissuaded from pursuing IVF if you need it. Talk to your doctor to develop a plan for what works best for your situation. For example, one 2006 study, looking at more than 2,000 cycles at 100 IVF centers, found that PGD reduced the miscarriage rate among women ages 35 to 40 from 19% to 14%, and among women over the age of 40, from 41% to 22%.
