Polycystic ovary syndrome and gestational diabetes mellitus association to pregnancy outcomes: A national register-based cohort study.

Introduction: It is well known that both women with polycystic ovary syndrome (PCOS) and women with gestational diabetes mellitus (GDM) have increased risks of adverse pregnancy outcomes, but little is known whether the combination of these two conditions exacerbates the risks. We explored risk estimates for adverse pregnancy outcomes in women with either PCOS or GDM and the combination of both PCOS and GDM.

Material and methods: Nationwide register-based historical cohort study in Sweden including women who gave birth to singleton infants during 1997-2015 (N = 281 806). The risks of adverse pregnancy outcomes were estimated for women exposed for PCOS-only (n = 40 272), GDM-only (n = 2236), both PCOS and GDM (n = 1036) using multivariable logistic regression analyses. Risks were expressed as odds ratios with 95% confidence intervals (CIs) and adjusted for maternal characteristics, including maternal BMI. Women with neither PCOS nor GDM served as control group. Maternal outcomes were gestational hypertension, preeclampsia, postpartum hemorrhage, and obstetric anal sphincter injury. Neonatal outcomes were preterm birth, stillbirth, shoulder dystocia, born small or large for gestational age, macrosomia, low Apgar score, infant birth trauma, cerebral impact of the infant, neonatal hypoglycemia, meconium aspiration syndrome and respiratory distress.

Results: Based on non-significant PCOS by GDM interaction analyses, we found no evidence that having PCOS adds any extra risk beyond that of having GDM for maternal and neonatal outcomes. For example, the adjusted odds ratio for preeclampsia in women with PCOS-only were 1.18 (95% CI 1.11-1.26), for GDM-only 1.77 (95% CI 1.45-2.15), and for women with PCOS and GDM 1.86 (95% CI 1.46-2.36). Corresponding adjusted odds ratio for preterm birth in women with PCOS-only were 1.34 (95% CI 1.28-1.41), GDM-only 1.64 (95% CI 1.39-1.93), and for women with PCOS and GDM 2.08 (95% CI 1.67-2.58). Women with PCOS had an increased risk of stillbirth compared with the control group (aOR 1.52, 95% CI 1.29-1.80), whereas no increased risk was noted in women with GDM (aOR 0.58, 95% CI 0.24-1.39).

Conclusions: The combination of PCOS and GDM adds no extra risk beyond that of having GDM alone, for a number of maternal and neonatal outcomes. Nevertheless, PCOS is still an unrecognized risk factor in pregnancy, exemplified by the increased risk of stillbirth.