Background: Polycystic ovary syndrome (PCOS) is closely associated with obesity but the prevalence of obesity varies between published studies. The objective of this research was to describe the prevalence of overweight and obesity, obesity and central obesity in women with and without PCOS, and to assess the confounding effect of ethnicity, geographical regions and the diagnostic criteria of PCOS on the prevalence.

Methods: MEDLINE, EMBASE, CINAHL, Cochrane Central Register of Controlled Trials (CENTRAL), and PSYCINFO were searched for studies reporting prevalence of overweight, obesity or central obesity in women with and without PCOS. Data were presented as prevalence (%) and risk ratio (RR) [95% confidence interval (CI)]. Random-effect models were used to calculate pooled RR.

Results: This systematic review included 106 studies while the meta-analysis included 35 studies (15129 women). Women with PCOS had increased prevalence of overweight [RR (95% CI) 1.95 (1.52, 2.50)], obesity [2.77 (1.88, 4.10)] and central obesity [1.73 (1.31, 2.30)] compared to women without PCOS. Caucasian women with PCOS had a greater increase in obesity prevalence than Asian women with PCOS compared to women without PCOS, [10.79 (5.36, 21.70) versus 2.31 (1.33, 4.00), P<0.001 between subgroups).

Conclusions: Women with PCOS had a greater risk of overweight, obesity and central obesity. Although our findings support a positive association between obesity and PCOS, our conclusions are limited by the significant heterogeneity between studies and further studies are now required to determine the source of this heterogeneity. Clinical management of PCOS should include prevention and management of overweight and obesity.