Parity and risk of ovarian cysts: Cross-sectional evidence from the Dongfeng-Tongji cohort study.

Little is known about the association between parity and the risk of ovarian cysts. The aim of this study was to examine the association between parity and the risk of ovarian cysts among a population of Chinese women. A total of 20 502 women aged 45-86 years from the Dongfeng-Tongji Cohort study completed baseline questionnaires, medical examination and provided baseline blood samples. Participants were categorized into four groups according to parity (one, two, three, and four or more live births). Logistic regression models were used to investigate the association between parity and the risk of ovarian cysts. The prevalence of ovarian cysts in the study population was 4.0% (816/20 502). Increasing parity was associated with decreasing risk of ovarian cysts without adjustment for any covariates and after age-adjusted model (P<0.001). After adjusting for potential confounders, women who had had four or more live births had lower risk of ovarian cysts (OR: 0.51; 95% CI: 0.27-0.96) compared with women who had had one live birth. There was a consistent but non-significant decreased risk of ovarian cysts for women who had had two, and three live births (OR: 0.85; 95% CI: 0.68-1.05) and (OR: 0.84; 95% CI: 0.59-1.20) respectively compared with women who had had one live birth. It was concluded that higher parity was associated with decreasing risk of ovarian cysts in this population of Chinese women. These findings could be helpful in decision making in clinical practice for gynecologists when evaluating women suspected to have ovarian cysts.