High normal blood pressure increase risks of developing adverse pregnancy outcomes

Abstract

This study evaluated the effects of high normal blood pressure (HNBP) in early pregnancy on adverse pregnancy outcomes. We conducted a multi-center and national representative retrospective cohort study. We defined high normal blood pressure as systolic blood pressure between 130-140mmHg or diastolic blood pressure between 85-90mmHg. We used multivariable logistic regression to examine the association of HNBP and risks of pregnancy outcomes. Of 69 687 normotensive women in early pregnancy, 5 798 (8.3%) fulfilled our definition of HNBP, 20 394 (29.3%) were in normal blood pressure group, and the rest 43 495 (62.4%) women had optimal blood pressure. The incidence rates of gestational hypertension, preeclampsia, gestational diabetes mellitus (GDM), premature birth, small for gestational age (SGA), caesarean section, placental abruption and perinatal mortality were 1.6%, 2.3%, 4.2%, 6.1%, 7.1%, 54.9%, 0.5% and 0.7% respectively. Compared to women who had optimal blood pressure, those with HNBP had significantly higher odds of preeclampsia (OR = 4.179, 95% CI 3.584, 4.873), gestational hypertension (OR = 6.050, 95% CI 5.071, 7.219), GDM (OR = 1.077, 95% CI 1.007, 1.153), premature birth (OR = 1.504, 95% CI 1.329, 1.702), SGA (OR = 1.329, 95% CI 1.177, 1.500) and cesarean delivery (OR = 1.583, 95% CI 1.379, 1.817). Our restricted cubic spline results supported positive dose-response relationships between continuous blood pressure and the odds of these pregnancy complications. HNBP in early pregnancy significantly increased the risk of developing preeclampsia, gestational hypertension, GDM, premature birth, SGA and cesarean delivery. Our study provided robust epidemiological evidences for monitoring HNBP in early pregnancy to reduce the risks of adverse pregnancy outcomes.