Are repeated miscarriages related to a smaller reserve of eggs?

This study evaluated whether repeated miscarriages were related to a woman's ovarian reserve (number of eggs). This study concluded that women who had repeated miscarriages were more likely to have a low ovarian reserve.

One cause of infertility is repeated miscarriages, also known as recurrent pregnancy loss. Between 1% and 2% of women have repeated miscarriages. In up to half of cases, there is no apparent cause. However, many miscarriages are due to abnormal pregnancies. If an egg has an unusual number of chromosomes (pieces of genetic material), the embryo will be abnormal. As a woman grows older, her eggs become more likely to have an unusual number of chromosomes. Having a low ovarian reserve may increase the chances of this occurring.

Ovarian reserve can be measured in several ways. Eggs develop in protective sacs called follicles. Follicles undergo different stages of development before eggs are produced (ovulation). One way to count the number of follicles (AFC count) uses ultrasound. Hormone levels can also be measured, such as AMH (produced by follicles). Whether women with a low ovarian reserve are more likely to have repeated miscarriages is unclear.

This study looked at the results of 15 studies that included 3,082 women. Some of the women had three or more miscarriages, while other women did not (control group).

Three studies looked at the effects of low levels of AMH (below 1 ng/mL). These studies found that women with repeated miscarriages were more likely to have low levels of AMH.

Another analysis looked at two studies (313 women). The authors found that women with repeated miscarriages were 2.77 times more likely to have low AMH levels. Women had a higher risk of low AMH if their miscarriages were unexplained.

Two studies looked at the effects of miscarriage on AFC count. Women with repeated miscarriages were 2.45 times more likely to have a low AFC count (7 follicles or fewer). 

This study concluded that women who had repeated miscarriages were more likely to have a low ovarian reserve. The authors suggest that low AMH and AFC levels could predict higher chances of miscarriage, but more studies are needed.

There were differences between the studies, which meant that not all data could be combined.