Am Fam Physician. 2023;108(4):411-412
Author disclosure: No relevant financial relationships.
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
Treating mild hypertension did not increase rates of fetal growth restriction or maternal or neonatal complications.1 The primary safety outcome was small-for-gestational-age birth weight below the 10th percentile. Secondary outcomes included composites of serious neonatal or maternal complications, preeclampsia, and preterm birth. The treatment group did not have a statistically significant increase in small-for-gestational age infants (11.2% vs. 10.4% for no treatment; adjusted RR = 1.04; 95% CI, 0.82 to 1.31; P = .76). The treatment and nontreatment groups had a similar incidence of serious maternal complications (2.1% vs. 2.8%; RR = 0.75; 95% CI, 0.45 to 1.26) and severe neonatal complications (2.0% vs. 2.6%; RR = 0.77; 95% CI, 0.45 to 1.30).
Recommendations From Others
Based on the findings of the 2022 RCT,1 the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine released statements supporting the treatment of mild hypertension in pregnancy.2,3 The 2022 RCT did not establish a target blood pressure, and there may be a target level below which pregnant people are at risk of fetal growth restriction.2 The International Society for the Study of Hypertension in Pregnancy recommends treating nonsevere chronic hypertension in pregnancy to a target blood pressure of 110 to 140/80 to 85 mm Hg.4
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