Association between obesity and the risk of uterine fibroids: a systematic review and meta-analysis

Uterine fibroids (UFs) are the most common form of sex steroid hormone-dependent benign tumours that grow in the walls of the uterus. Several observational studies have examined the association between obesity and the risk of UFs, but findings are inconsistent. The objective of this systematic review and meta-analysis is to further examine the association of obesity with the risk/prevalence of UFs.A literature search was performed in three databases (PubMed, EMBASE and Web of Science) from 1 January 1992 to 30 May 2020. We used random-effect models to calculate the pooled ORs with corresponding 95% CIs. Additionally, we performed a dose-response meta-analysis to analyse the effect of body mass index (BMI), weight change since age 18, waist-to-hip ratio and waist circumference on the risk/prevalence of UFs.A total of 22 articles, covering 24 studies including 325 899 participants and 19 593 cases, were selected based on our inclusion criteria. We found a positive association between obesity and the risk/prevalence of UFs (OR, 1.19; 95% CI, 1.09 to 1.29). Among participants with the highest BMI, the pooled OR was 1.19 (1.09 to 1.31) when compared to participants with normal BMI. For weight change since age 18, the pooled OR (95% CI) of UFs was 1.26 (1.12 to 1.42) among the highest change group when compared with no change. Additionally, our meta-analysis indicated the relationship of BMI with risk of UFs to be an inverse J-shaped pattern.The results of this meta-analysis suggest that obesity may increase the risk/prevalence of UFs, and the association is non-linear.