Reproductive history and pregnancy outcomes in women with endometriosis findings from the national health and nutrition examination surveys (NHANES) 1999–2002

Abstract

This unique study compared select demographic, reproductive, and pregnancy characteristics among women with and without endometriosis in a representative sample of the US population. Cross-sectional analysis of the 1999–2002 NHANES, a population-based survey that collects health and nutrition information. A total of 3,131 women, ages 20–54, were eligible for the endometriosis-related questions within the Reproductive Health Questionnaire. Outcomes of interest included: age at first and last birth, history of oral contraceptive (OC) use, number of live births, spontaneous and induced abortions. Simple logistic and linear regression models were fitted, in which all outcomes of interest were regressed on endometriosis status. History of OC use was analyzed to determine if it modified the effect of endometriosis on the outcome. Final models were adjusted for select demographic characteristics. The prevalence of endometriosis was 9.3%. These women were more likely to have a history of OC use compared to those without endometriosis (89.7% vs. 78.1%; P<0.001). History of OC use did not affect age at first and last birth. Women with endometriosis were (1) less likely (P[LT] 0.001) to be single (8.1% vs. 20.7%), (2) more likely to have more than a high school education (92.8% vs. 89.9%), and (3) were more likely to be US born (93.6% vs. 84.3%). There was a greater proportion of whites with endometriosis (86.6% vs. 66.8%, P<0.001) and women with endometriosis were more likely to have a household income greater than $45,000 (62.8% vs. 51.5%; P<0.05). Odds of pregnancy were not statistically different among women with and without endometriosis. Women with endometriosis were more frequently barren compared to those without endometriosis (0.58; 95% CI: 0.33–1.01). Compared to women without endometriosis, women with endometriosis differed in their reproductive histories and demographic profiles: they were more likely to start and stop having children at a younger age, had a decreased odds of ever having had a live birth, and were more likely to be married, white and educated. These characteristics may be associated with greater awareness or increased opportunity for diagnosis of the disease. Using data obtained from a population-based, complex survey design, this study was able to substantiate findings from prior studies limited by selection bias.