Endometriosis — in which the cells of the endometrial lining grow outside of the uterus — is one of the most commonly-cited factors in infertility issues. But according to a new analysis, the actual endometriosis-related risk for infertility may be only half of what we thought.
For the study, published online earlier this month in the journal Human Reproduction, researchers looked at data for 58,427 women who participated in a major national health survey that asked about fertility issues and other major health problems. All of the women included in the new analysis were younger than 40, married, and premenopausal. Of those women, 3,537 of them had been diagnosed with endometriosis via laparoscopy (the gold-standard method).
Results showed that, as expected, those who had endometriosis were more likely to have issues with fertility. Indeed, among women below the age of 35, an endometriosis diagnosis more than doubled participants' risk for infertility. But the difference actually wasn't anywhere near as large as the researchers anticipated. Although previous estimates vary wildly, most suggest the risk of infertility is twice as high as what researchers found in the current study.
"Women with endometriosis are definitely at higher risk for infertility," study author Stacey A. Missmer, Sc.D tells R29. But she adds that there are two major take-home messages here: "First, endometriosis does not always lead to infertility." Despite the increased risk, 83% of women with endometriosis had children by the age of 40 in this study. "And second," she continues, "it's now our responsibility to figure out who is most at risk for infertility among women with endometriosis."
Between five and 10% of women in the general population suffer from endometriosis. Dr. Missmer says that previous studies may have overestimated the link to infertility because most only looked at women already diagnosed with infertility and/or endometriosis. But her study, instead, traced the way patients' chances of conceiving changed over time, which is a more reliable way to measure the effects of endometriosis on fertility.
Endometriosis can also affect fertility in a variety of ways: influencing egg quality, messing with the menstrual cycle, or causing higher levels of inflammation. And Dr. Missmer says researchers are still working out exactly how these things affect fertility overall — and how they differ between individuals. Some of those obstacles might be easier to overcome than others. Identifying the factors that matter earlier on in the process could, one day, help those hoping to become pregnant save time, effort, and money.