This study aims to investigate the effect of endometriosis (EMs) on fertility and to assess the causal relationship between EMs and fertility using two-sample Mendelian randomization (MR). We conducted an observational study using data from 1999 to 2006, based on the National Health and Nutrition Examination Survey database. The effect of EMs on fertility was assessed using the chi-square test or t test. The genome-wide association study collected 147,343 single-nucleotide polymorphisms associated with EMs and 7,974,415 single-nucleotide polymorphisms for the number of children. The number of children was used as the outcome variable, and EMs as the exposure factor. The inverse variance weighted method was used to evaluate the association between EMs and the number of children. The maximum likelihood ratio method, Mendelian randomization pleiotropy residual sum and outlier test, and MR-Egger regression were used for sensitivity analysis. A total of 4933 women were included in the observational study based on whether participants had EMs. There were 337 women in the EMs group and 4596 in the non-EMs group. The number of children born to women in the EMs group was 1.91 ± 1.078, which was significantly lower than that of the non-EMs group (2.26 ± 1.438; t = -4.287, P .05). The MR study also confirmed that EMs was associated with the ratio of live births (odds ratio = 0.989, 95% confidence interval = 0.981-0.996, P .05). EMs reduces pregnancies resulting in live births. Our results provide some reference significance for revealing the impact of EMs on fertility.
Liling et al. (Fri,) studied this question.