Objective: Studies regarding the effect of parity on endometriosis are in controversy. This study is the first, to our knowledge, to evaluate the association between parity and risk of endometriosis. The purpose of performing this meta-analysis was evaluating the association between parity and risk of endometriosis.
Materials and Methods: We conducted an advanced search in PubMed, Scopus, and Web of Science to explore data from the beginning of 2000. We performed Eggers and Beggs tests to evaluate publication bias. The Q-statistic test and I-squared (I2) test were used to estimate the heterogeneity among studies. The association between parity and risk of endometriosis was determined by the random effects model.
Results: In total, we included 17 studies in the present meta-analysis with 78,644 subjects. The pooled overall OR was 0.53 (95% CI: 0.40, 0.67). The significant heterogeneity was observed among these studies (I2=95.7%, p<0.001).
Conclusion: The present study is the first meta-analysis that showed that parity is a protective factor for endometriosis. In addition, the risk of endometriosis decreased with higher parity based on subgroup analysis.