Physiologic blood pressure patterns in pregnancies with mild chronic hypertension.

Objectives: To assess physiologic blood pressure (BP) changes throughout pregnancy in patients with mild chronic hypertension (CHTN) who do and do not develop preeclampsia (PEC), compared to patients with normal BP.

Study Design: Retrospective cohort of singleton gestations with CHTN at a single tertiary center from 2000 to 2014 and a randomly selected cohort of patients without CHTN and normal pregnancy outcomes (NML) in the same time period with BP measurements available <12 weeks gestational age.

Main Outcome Measures: The primary outcome was gestational age (GA) at nadir of systolic and diastolic BP. Secondary outcomes included perinatal death, umbilical cord pH, maternal and neonatal length of stay, GA at delivery, and mode of delivery. Quadratic mixed models were used to estimate SBP and DBP throughout gestation.

Results: Of 367 pregnancies with CHTN, 268 (73%) had CHTN without PEC and 99 (27%) had CHTN with PEC; 198 NML pregnancies were used as a comparison group. The median GA nadir for patients in the NML, CHTN without PEC, and CHTN with PEC for SBP were 20, 24, and 21, respectively. For DBP, the median GA nadir were 22, 24, and 21 for patients in the NML, CHTN without PEC, and CHTN with PEC cohorts, respectively. Adverse secondary outcomes were more frequent in patients with CHTN who developed PEC.

Conclusions: BP trajectories in pregnancy are different between patients with CHTN with PEC, CHTN without PEC, and patients with normal BP. These findings may be useful in assessing patients' risks for developing preeclampsia during pregnancy.