Infertility and ovarian cancer risk: Evidence from nine prospective cohort studies.

Epidemiological studies have investigated the relationship between infertility and the risk of ovarian cancer (OC); however, the results have been inconsistent. We therefore conducted the first meta-analysis to update and quantify the aforementioned association based on prospective cohort studies. Studies were identified by searching PubMed, EMBASE and Web of Science databases up to January 8, 2020. We extracted data from the studies and performed quality assessments. Summary relative risks (RRs) with 95% confidence intervals (CIs) were calculated using a random-effects model. Publication bias, and subgroup, meta-regression and sensitivity analyses were also conducted. Nine prospective cohort studies with a total of 10 383 OC cases and 6 278 830 participants were included in the present study. The summary RR of the association between infertility and the risk of OC was 1.51 (95% CI: 1.35-1.69), with low heterogeneity. Positive associations were observed in most subgroup analyses stratified by predefined factors, including region, duration of follow-up, study quality, causes of infertility, invasiveness of OC, infertility treatment status and adjustment of potential confounding parameters. No significant publication bias was detected. Our findings suggest that infertility in women were associated with an increased risk of OC.