The trajectory of body mass index in women with PCOS in two cohorts of Australian women

Abstract

BackgroundCross sectional studies show a consistent association between a diagnosis of PCOS and higher body weight. It is unclear, however, how the trajectory of gain in BMI differs between women who have PCOS and those who do not over time.MethodsWe used data from two population-based cohort studies of Australian women: 8 576 born in 1989-95 (“millennials”) and 10 502 born in 1973-78 (“Gen X”). We used linear mixed regression models to compare the average annual increase in BMI in women who reported a diagnosis of PCOS with those who did not in each cohort. In the younger cohort, we compared the annual increase in BMI before and after diagnosis.ResultsIn the cohort born 1989-95, 1 372 women (16.0%) reported a diagnosis of PCOS. The average annual increase in BMI in women who reported a diagnosis of PCOS was 0.41 kg/m2/year (0.39–0.43), greater than the annual increase than in women who did not report the diagnosis, 0.34 kg/m2/year (0.33–0.35). In the 590 women in this cohort where the timing of the diagnosis could be estimated, the average annual increase in BMI slowed from 0.48 kg/m2/year (0.43–0.53) before diagnosis to 0.37 kg/m2/year after diagnosis (0.33–0.41). In the cohort born 1973-78, 940 women (9.0%) reported a diagnosis of PCOS. The average annual increase in BMI in women who reported a diagnosis of PCOS was 0.25 kg/m2/year (0.23–0.27), greater than the annual increase than in women did not report the diagnosis, 0.20 kg/m2/year (0.19–0.21).ConclusionsWomen who report a diagnosis of PCOS have a higher rate of BMI gain than women who do not have the diagnosis. The rate appears to slow after the diagnosis. The rate of BMI gain was higher in the “millennial” cohort of women than in the “GenX” cohort of women at the same age.