Context: Women with polycystic ovary syndrome (PCOS) have increased risk for pregnancy complications, possibly related to pre-existing obesity and excessive gestational weight gain (GWG).
Objectives: To assess the contributions of diagnosis and preconception weight on GWG and perinatal outcomes.
Research design and methods: Prospective cohort study of singleton pregnancies in PCOS (n = 164) and ovulatory controls (n = 176) from infertility treatment.
Main outcome measures: GWG, birthweight, pregnancy complications.
Results: From preconception baseline, normal-weight women with PCOS gained 2.3 pounds more during the first trimester (95% CI, 0.3 to 4.3; P = 0.02), and by the end of the second trimester, 4.2 pounds more than controls (95% CI, 0.7 to 7.7; P = 0.02). Women who were overweight with PCOS gained significantly more weight than did controls by the end of the second trimester (5.2 pounds; 95% CI, 0.2 to 10.2; P = 0.04), whereas women with obesity and PCOS and control women had similar weight gain throughout pregnancy. Within normal-weight, overweight, and obese groups, prevalence of pre-eclampsia and gestational diabetes did not differ between the PCOS and control groups, nor was there a difference in birthweight. Preconception body mass index (BMI) was significantly associated with GWG; for every 1-kg/m2 increase in preconception BMI, GWG decreased by 0.62 pounds (95% CI, -0.85 to -0.40; P < 0.001).
Conclusions: Women with PCOS who are of normal weight or are overweight before conception experience more GWG than do ovulatory controls. Within normal-weight, overweight, and obese groups, rates of perinatal complications do not significantly differ between women with PCOS and controls. Preconception BMI is the strongest predictor of GWG.