Birth outcomes in mothers with hypertensive disorders and polycystic ovary syndrome: a population-based cohort study

Abstract STUDY QUESTION Is polycystic ovary syndrome (PCOS) associated with higher risks of extreme birth size and/or preterm birth in mothers with different hypertension types? SUMMARY ANSWER PCOS was associated with additional risks of preterm birth in mothers with chronic hypertension and in singleton pregnancies of mothers with pre-eclampsia, and with higher risks of offspring born large for gestational age (LGA) in mothers with gestational hypertension. WHAT IS KNOWN ALREADY Women with PCOS are more likely to develop gestational hypertension, pre-eclampsia, and chronic hypertension. Although adverse birth outcomes have been frequently reported in mothers with PCOS, such associations in the setting of a hypertensive disorder remain unknown. STUDY DESIGN, SIZE, DURATION This is a population-based cohort study including all live births 2004–2014 in Finland (n = 652 732). To ensure diagnosis specificity, mothers with diagnoses that could cause signs and symptoms resembling PCOS were excluded. PARTICIPANTS/MATERIALS, SETTING, METHODS Maternal diagnoses of PCOS, gestational hypertension, chronic hypertension, and pre-eclampsia were identified from the Finnish national registries. Generalized estimating equation and multivariable logistic regression were used to assess the adjusted odds ratio (aOR) and 95% CIs of preterm birth, very preterm birth, and offspring being small for gestational age (SGA) or LGA in hypertensive mothers with or without PCOS, using normotensive mothers without PCOS as reference. MAIN RESULTS AND THE ROLE OF CHANCE Of 43 902 (6.7%) mothers with hypertensive disorders, 1709 (3.9%) had PCOS. Significant interactions were detected for PCOS with hypertension on preterm birth, very preterm birth, offspring born SGA and LGA (Fpreterm = 504.1, Pinteraction < 0.001; Fvery preterm = 124.2, Pinteraction < 0.001; FSGA = 99.5, Pinteraction < 0.001; FLGA = 2.7, Pinteraction = 0.012, respectively). Using mothers with no hypertensive disorder and no PCOS as reference, the risks of preterm and very preterm birth were overrepresented in non-PCOS mothers with chronic hypertension or pre-eclampsia. PCOS was associated with higher risks of preterm birth (aORPCOS 4.02, 3.14–5.15 vs aORnon-PCOS 2.51, 2.32–2.71) in mothers with chronic hypertension, with significant interaction between the exposures (F = 32.7, Pinteraction < 0.001). PCOS was also associated with a higher risk of preterm birth in singleton pregnancies of mothers with pre-eclampsia (aORPCOS 7