1 - Treatment for Mild Chronic Hypertension during Pregnancy: Is tighter better?

The Chronic Hypertension and Pregnancy (CHAP) trial demonstrated improved outcomes with treatment to a BP goal < 140/90 compared to < 160/105 mmHg in pregnant women with chronic hypertension (cHTN). The American Heart Association now defines stage 1 cHTN systolic BP 130-139 or diastolic BP 80-89 and recommends BP goal < 130/80 in the non-pregnant population. Our primary objective was to evaluate the hypothesis that lowering maternal BP to < 130/80 compared to 130-139/80-89 reduces adverse maternal and fetal outcomes.  

Study Design:

This is a planned secondary analysis of CHAP, an open label, multicenter, randomized controlled trial of 2408 women with chronic hypertension. Patients were included in this analysis if mean BP after randomization to treatment vs. none was < 140/90, had longitudinal BP data during pregnancy and complete outcome data available. BP was categorized by averaging clinic BPs throughout pregnancy after enrollment into SBP < 130 and DBP < 80 vs. SBP 130-139 and/or DBP 80-89. The primary outcome was a composite morbidity (preeclampsia, preterm birth < 35 weeks, abruption, fetal death). Secondary outcomes included small for gestational age (SGA) as well additional fetal and maternal outcomes. Log-binomial regression was performed, adjusting for confounding variables.

Results:

There were 2164 participants included in this analysis; 768 (35.5%) had mean BP < 130/80 and these participants were older, more likely to be on BP medication, had lower enrollment BP and BMI, and were more likely to be in the active treatment arm. The primary outcome and components (severe preeclampsia and indicated birth < 35 weeks) were significantly lower if BPs < 130/80 (Table 2). SGA was not different between the two groups. Several neonatal outcomes were also lower if BP < 130/80.

Conclusion:

Maintaining women to lower goals (BP < 130/80) is associated with improved maternal and fetal outcomes. Furthermore, as more women in the lower BP group were on medication, this suggests that initiating antihypertensive therapy with a BP goal of < 130/80 may be beneficial.