Background: Women with polycystic ovary syndrome (PCOS) have increased risk factors and adverse outcomes during pregnancy. Previous studies highlight the need to assess these outcomes using clear and consistent definitions, independent of the confounding impact of higher body mass index (BMI).
Objectives: To compare pregnancy outcomes between those with and without PCOS among women at high cardiometabolic risk.
Methods: A sub-study of the Treatment of Booking Gestational Diabetes Mellitus (TOBOGM) multicentre randomised controlled trial involving singleton pregnancies with risk factors for hyperglycaemia undergoing an additional early Oral Glucose Tolerance Test before 20 weeks’ gestation. Outcomes: 1) prevalence of self-reported PCOS in the TOBOGM study cohort, 2) the distribution of PCOS status across sociodemographic and pregnancy characteristics, 3) the relationship between PCOS status and maternal and neonatal complications and 4) the association between early GDM (eGDM), later GDM (lGDM) and PCOS status.
Results: A total of 3645 women with one or more risk factors for GDM, including PCOS status, were included in the study. The prevalence of PCOS was 17.1%, (95% CI 0.159, 0.183). An initial OGTT was performed at a mean (±SD) gestation of 15.6 ±2.5 weeks. At the first antenatal visit, women with PCOS were of lower maternal age (30.6 v 31.3 years; P<0.001). The PCOS group had a higher mean pre-pregnancy BMI (28.5 kg/m2 ; v 27.0 kg/m2 , P<0.001), higher BMI (29.8 kg/m2 v 28.1 kg/m2; P<0.001) and higher systolic blood pressure (110.3 mmHg v 109.1 mmHg; P=0.026). Diastolic blood pressure, rates of eGDM, early OGTT fasting blood glucose, 1-hour glucose and 2-hour glucose levels did not differ between groups. Rates of pregnancy induced hypertension (11.3% v 9.4, P=0.157) and induction of labour (41.9% v 39.1%, P=0.213) were not significantly different. There were no differences between the groups in rates of pre-eclampsia, GDM at 24 weeks, mean maternal gestational weight gain, rates of medication use for GDM, caesarean section, premature birth <37 weeks or perineal injury. In the PCOS group, shoulder dystocia was more prevalent (5.1% v 3.0%, P=0.012). There were no differences between the groups with respect to birth weight > 4500g, large or small for gestational age, neonatal respiratory distress or need for phototherapy.
Conclusions: In a group of pregnant women selected for having at least one high cardiometabolic risk factor, PCOS is not associated with a higher risk of pregnancy complications. Women with PCOS were at increased risk of shoulder dystocia, but no differences were found in other neonatal outcomes.