Pregnancy Outcomes in Women Who Developed Elevated Blood Pressure and Stage I Hypertension after 20 Weeks Gestation.

Abstract

The American College of Obstetrics (ACOG) threshold for hypertension (≥140/90 mmHg) differs from those of the American College of Cardiology (ACC) and the American Heart Association (AHA). It is unknown if ACC/AHA hypertension levels are associated with adverse pregnancy outcomes (APOs) after 20 weeks gestation. The purpose of this study is to analyze APOs in women with blood pressure (BP) in the elevated or stage 1 range after 20 weeks gestation. This was a secondary analysis of the nuMoM2b prospective cohort study of 10,038 nulliparous, singleton pregnancies between 2010-2014. BP was measured at 3 visits during the pregnancy using a standard protocol. Women without medical comorbidities, with normal BP by ACC/AHA guidelines [systolic BP (SBP)<120 and diastolic BP (DBP)<80 mmHg] up to 22 weeks were included. Exposure was BP between 22-29 weeks gestation: normal (SBP<120 and DBP<80 mmHg), elevated (SBP 120-129 and DBP<80 mmHg), and stage 1 (SBP 130-139 or DBP 80-89 mmHg). The primary outcome was hypertensive disorder of pregnancy (HDP) at delivery. Secondary outcomes included fetal growth restriction (FGR), placental abruption, preterm delivery, and cesarean delivery. Multivariable-adjusted odds ratio (aORs) and 95% confidence intervals (CIs) were estimated using logistic regression models. Of 4,460 patients that met inclusion criteria, 3,832 (85.9%) had BP in the normal range, 408 (9.1%) in elevated, and 220 (4.9%) in stage 1 range between 22-29 weeks. The likelihood of HDP was significantly higher in women with elevated BP (aOR 1.71, 95%CI 1.18,2.48) and stage 1 BP (aOR 2.79, 95%CI 1.84,4.23) compared to normal BP (p<0.001). Stage 1 BP had twice odds of FGR (aOR 2.33, 95%CI 1.22,4.47) and elevated BP had three times odds of placental abruption (aOR 3.03; 95%CI 1.24,7.39). Elevated or stage 1 BP >20 weeks of pregnancy are associated with HDP, FGR, and placental abruption.