BACKGROUND AND PURPOSE:

• Tita et al. (NEJM, 2022) evaluated the benefits and safety of pharmacologic antihypertensive therapy during pregnancy for women with mild chronic hypertension

METHODS:

• Open-label, multicenter, randomized trial
  • Chronic Hypertension and Pregnancy (CHAP)
• Participants
  • Mild chronic hypertension (new or known)
    • New: SPB ≥140 mm Hg and/or DBP ≥90 mm Hg on ≥2 occasions at least 4 hours apart <20 weeks without chronic hypertension
    • Known: Documentation of elevated blood pressure and previous or current antihypertensive therapy (including lifestyle measures)
  • Singleton fetus
  • <23 weeks
• Interventions
  • Active-treatment group
    • Antihypertensive medications recommended for use in pregnancy (see ObG Related Entry, below)
  • Control group
    • No treatment unless severe hypertension (SBP ≥160 mm Hg or DBP ≥105 mm Hg)
• Primary outcome
  • Composite
    • Preeclampsia with severe features | Medically indicated preterm birth <35 weeks | Placental abruption | Fetal neonatal death
• Safety outcome
  • Small-for-gestational-age (SGA)
    • Birth weight <10th percentile for gestational age
• Secondary outcomes
  • Composites of serious neonatal or maternal complications, preeclampsia, and preterm birth

RESULTS:

• Active treatment: 1208 participants | Control: 1200 participants
• The incidence of the primary composite outcome was lower in the active treatment group
  • Active treatment: 30.2%
  • Control: 37.0%
  • Adjusted risk ratio (aRR) 0.82 (95% CI, 0.74 to 0.92); P<0.001
• There was no significant difference in the percentage of SGA
  • Active treatment: 11.2%
  • Control: 10.4%
  • aRR 1.04 (95% CI, 0.82 to 1.31); P=0.76
• There was also no significant difference in incidence of serious maternal or neonatal outcomes
  • Serious maternal complications
    • Active treatment: 2.1%
    • Control: 2.8%
    • RR 0.75 (95% CI, 0.45 to 1.26)
  • Severe neonatal complications
    • Active treatment: 2.0%
    • Control: 2.6%
    • RR 0.77 (95% CI, 0.45 to 1.30)
• There was a reduction in the risk of preeclampsia and preterm birth in the active treatment group
  • Preeclampsia
    • Active treatment: 24.4%
    • Control: 31.1%
    • RR 0.79 (95% CI, 0.69 to 0.89)
  • Preterm birth
    • Active treatment: 27.5%
    • Control 31.4%
    • RR 0.87 (95% CI, 0.77 to 0.99)

CONCLUSION:

• Pharmacological antihypertensive treatment in pregnant women with mild chronic hypertension successfully improved pregnancy outcomes without an increased risk for SGA
• The authors state

Our findings support the treatment of pregnant women with chronic hypertension with a blood-pressure target of less than 140/90 mm Hg, including the continuation of their established antihypertensive therapy

Addendum

• ACOG released a practice advisory in response to the CHAP trial which states

ACOG recommends utilizing 140/90 as the threshold for initiation or titration of medical therapy for chronic hypertension in pregnancy, rather than the previously recommended threshold of 160/110

• SMFM has also addressed the CHAP trial

SMFM recommends treatment with antihypertensive therapy for mild chronic hypertension in pregnancy to a goal BP <140/90 mm Hg

Learn More – Primary Sources:

Treatment for Mild Chronic Hypertension during Pregnancy

ACOG: Clinical Guidance for the Integration of the Findings of the Chronic Hypertension and Pregnancy (CHAP) Study

SMFM Statement: Antihypertensive therapy for mild chronic hypertension in pregnancy (The CHAP Trial)

Related ObG Topics:

Chronic Hypertension in Pregnancy: Diagnosis and BP Measurement

Chronic Hypertension in Pregnancy: Evaluation and Management

Labetalol or Nifedipine for Chronic Hypertension in Pregnancy?

Impact of Daily Aspirin for Prevention of Preeclampsia among Women with Chronic Hypertension

New ACC/AHA Hypertension Guidelines: How Have They Changed the Prevalence of Isolated Diastolic Hypertension in the United States?