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Objective The American College of Obstetrics threshold for hypertension (≥140/90 mm Hg) 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.

Study Design This was a secondary analysis of the nuMoM2b prospective cohort study of 10,038 nulliparous, singleton pregnancies between 2010 and 2014. BP was measured at three 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 mm Hg) up to 22 weeks, were included. Exposure was BP between 22 and 29 weeks gestation: normal (SBP < 120 and DBP < 80 mm Hg), elevated (SBP: 120–129 and DBP < 80 mm Hg), and stage 1 (SBP: 130–139 or DBP: 80–89 mm Hg). 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.

Results 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 and 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).

Conclusion Elevated or stage 1 BP >20 weeks of pregnancy are associated with HDP, FGR, and placental abruption.

Key Points

Elevated and stage 1 BP increases risk for HDP.

Elevated BP increases risk for placental abruption.

Stage 1 BP increases risk for FGR.

Keywords blood pressure - chronic hypertension - adverse pregnancy outcomes - preeclampsia - hypertension - American College of Cardiology - American Heart Association Note

These findings were presented in poster format at the 43rd Annual Pregnancy Meeting, Society for Maternal-Fetal Medicine, in 2023.

Publication History

Received: 06 February 2024

Accepted: 24 March 2024

Accepted Manuscript online:
03 April 2024

Article published online:
23 April 2024

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