(606) Association between initial prenatal blood pressure and development of hypertensive disorders

The thresholds used for diagnosing chronic hypertension (cHTN) in the nonpregnant population were lowered in 2017 due to the association between increasing cardiovascular disease risk and increasing blood pressure (BP). The categories include Normal, Elevated, Stage 1, and Stage 2, where Stage 2 is the threshold used for diagnosing hypertension (HTN) in pregnancy. It is well known that pregnant patients with cHTN, previously diagnosed by systolic ≥ 140 or diastolic ≥ 90, are at increased risk of maternal and fetal / neonatal complications. It is less clear how 2017 definitions are associated with pregnancy outcomes. Our goal was to investigate the association between a patient’s BP category, determined at the initial prenatal visit, and the development of HTN in pregnancy.

Study Design:

This was an IRB-approved retrospective cohort study. Our database included patients who delivered at our institution between 2017 and 2022. We included patients with singleton gestations and were seen in the first trimester; we excluded those with cHTN. Using initial BPs, we categorized patients based on 2017 definitions and compared rates of hypertensive disorders and other maternal / fetal adverse outcomes that developed during pregnancy. ANOVA, chi-square, and logistic regression were used to calculate significance and odds ratios.

Results:

626 women were included. The mean initial prenatal visit occurred at 7.6 +/- 2.5 weeks. Overall, BP category was significantly associated with development of hypertensive disorders. 14% of patients in the Normotensive cohort developed gestational HTN or preeclampsia without severe features, and this rate increased to 25% and 49% for the Elevated and Stage I cohorts, respectively (p < 0.001). This association remained significant after controlling for BMI, age, and race/ethnicity.

Conclusion:

In our patient population, we found that as BP category increased, so did the risk of developing HTN. Patients’ first trimester BPs may be used to help identify those at risk of developing HTN in pregnancy.