Pregnancy, perinatal and childhood outcomes in women with and without polycystic ovary syndrome and metformin during pregnancy: a nationwide population-based study

BACKGROUND: Polycystic Ovary Syndrome (PCOS) is an endocrine disorder that affects women in reproductive age and represents an unfavourable risk factor for several pregnancy and perinatal outcomes. Despite, no guidelines or pharmaceutical strategies for treating PCOS during pregnancy are available. The aim of this study is to determine the association between polycystic ovary syndrome with or without metformin and the pregnancy, perinatal outcomes as well as the risk of obesity in children born to these mothers. METHODS: In this nationwide population-based cohort study based in Swedish population, all singleton births (n = 1,016,805) from 686,847 women since 2006 up to 2016 were included. Multivariable logistic and Cox regression modelling with odds ratios (OR) and hazard ratios (HR) and 95% confidence intervals were used to study the association between the exposure of maternal PCOS, metformin during pregnancy (or the combination of both) and: 1) Pregnancy outcomes: preeclampsia, gestational diabetes, caesarean section, and acute caesarean section, 2) Perinatal outcomes: preterm birth, stillbirth, low birth weight, macrosomia, Apgar < 7 at 5 min, small for gestational age and large for gestational age, and 3) Childhood Obesity. RESULTS: PCOS in women without metformin use during pregnancy was associated with higher risks of preeclampsia (OR = 1.09, 1.02–1.17), gestational diabetes (OR = 1.71, 1.53–1.91) and caesarean section (OR = 1.08, 1.04–1.12), preterm birth (OR = 1.30, 1.23–1.38), low birth weight (OR = 1.29, 1.20–1.38), low Apgar scores (OR = 1.17, 1.05–1.31) and large for gestational age (OR = 1.11, 1.03–1.20). Metformin use during pregnancy (in women without PCOS) was associated with a 29% lower risks of preeclampsia (OR = 0.71, 0.51–0.97), macrosomia and large for gestational age. Obesity was more common among children born to mothers with PCOS without metformin (HR = 1.61, 1.44–1.81); and those with metformin without PCOS (HR = 1.67, 1.05–2.65). PCOS with metformin was not associated with any adverse outcome. CONCLUSION: PCOS was associated with increased risks of adverse pregnancy and perinatal outcomes and childhood obesity. Metformin appears to reduce these risks in mothers with polycystic ovary syndrome and their children; but may increase the risk of childhood-obesity in children form women without PCOS. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12958-022-00905-6.