Clinical Question

Should medication be prescribed for mild chronic hypertension in pregnancy?

Evidence-Based Answer

Evidence and expert opinion support treating mild chronic hypertension in pregnancy with approved antihypertensives. (Strength of Recommendation: B, randomized controlled trial [RCT].)

Evidence Summary

Evidence and expert opinion previously suggested that nonsevere chronic hypertension should not be treated during pregnancy because lowering the patient’s blood pressure too much could lead to placental hypoperfusion, fetal growth restriction, preeclampsia, or preterm birth.

In a 2022 RCT of 2,408 women with singleton pregnancies and mild chronic hypertension (i.e., blood pressure less than 160/100 mm Hg) before 23 weeks’ gestation, participants were randomized to receive antihypertensives approved for use in pregnancy (active treatment group) or no treatment unless they met criteria for severe hypertension (i.e., systolic blood pressure of 160 mm Hg or greater or diastolic blood pressure of 105 mm Hg or greater).¹ The primary outcome was a composite of preeclampsia with severe features, medically indicated preterm birth at less than 35 weeks’ gestation, placental abruption, or fetal or neonatal death. Secondary outcomes included preeclampsia and preterm birth. The primary outcome was less common in the active treatment group (30.2% vs. 37.0% for no treatment; adjusted risk ratio = 0.82; 95% CI, 0.74 to 0.92; P < .001; number needed to treat [NNT] = 15).¹ The active treatment group also had a lower incidence of preeclampsia (24.4% vs. 31.1%; risk ratio [RR] = 0.79; 95% CI, 0.69 to 0.89; NNT = 15) and preterm birth (27.5% vs. 31.4%; RR = 0.87; 95% CI, 0.77 to 0.99; NNT = 26).¹