As a fertility specialist, I have friends, family and of course my patients who confide in me after having a miscarriage. Losing a pregnancy is an extremely emotional and upsetting event, no matter how early it occurs. Women, especially those undergoing fertility treatment, become emotionally attached to a pregnancy often at the time of the first positive test. But I’ll let you in on a little secret – the vast majority of reproductive aged women experience an early pregnancy loss at some point. Now this of course does not take away from the disappointment and sadness from such a loss, but perhaps there is some comfort in knowing you’re not alone.
The most common questions I hear from woman having one or more miscarriages are (1) why did this happen and (2) will it happen again. The first things you should know is that having a miscarriage does not necessarily make you prone to having another. In fact, the most likely outcome with your next positive pregnancy test is a healthy baby. Knowing this gives some relief to women who are terrified after having a miscarriage that they may not be able to have children.
In regards to why all pregnancies do not result in the birth of a baby (in fact about 25% of all clinically recognized pregnancies) – the most common reason is that the embryo that created that particular pregnancy was not genetically normal. Usually it’s due to aneuploidy – an incorrect number of chromosomes. Although there are rare conditions that make some couples more likely to create aneuploid pregnancies, it’s more likely that these genetically abnormal embryos stem from egg and/or sperm quality. For the most part, when an infertility doctor discusses “egg quality” he or she is likely referring to the DNA within the egg. A poor quality egg is likely to result in an abnormal embryo that will either not create a pregnancy or will result in miscarriage. Fortunately, all of the eggs in the ovaries do not have the same quality. So for most women, the chance of having a miscarriage is depends on the quality of the ovulated egg. The unfortunate reality however is that as women age, the percentage of eggs that have a good enough quality to lead to a healthy pregnancy declines. Increasing age makes achieving pregnancy more difficult and increases the risk of miscarriage. But for women of the same age, having a history of one or even two prior miscarriages does not significantly increase the likelihood of having another compared to a woman of similar age who has not had a pregnancy loss before.