Control of Hypertension in Pregnancy

Posted by • January 30th, 2015

In a trial comparing less-tight control of hypertension (target diastolic blood pressure, 100 mm Hg) with tight control (85 mm Hg) among pregnant women, rates of pregnancy loss, high-level neonatal care, and serious maternal complications were similar between groups.

Blood-pressure targets for women with nonsevere hypertension during pregnancy are much debated. Relevant randomized, controlled trials have been small and of moderate or poor quality; tight control (the use of antihypertensive therapy to normalize blood pressure) has been associated with maternal benefits (e.g., a decrease in the frequency of severe hypertension and possibly in the rate of antenatal hospitalization) but sometimes, though not consistently, with perinatal risks (e.g., poor fetal growth and well-being). The Control of Hypertension in Pregnancy Study (CHIPS) was designed to compare less-tight control with tight control of nonproteinuric, nonsevere hypertension in pregnancy with respect to perinatal and maternal outcomes.

Clinical Pearls

– How common is hypertension among pregnant women?

Almost 10% of pregnant women have hypertension; hypertension is preexisting in 1% have preexisting hypertension, gestational hypertension without proteinuria develops in 5 to 6%, and preeclampsia develops in 2%. Preexisting hypertension and gestational hypertension before 34 weeks are associated with an increased risk of perinatal and maternal complications.

How does tight control as compared to less-tight control of nonsevere, nonproteinuric hypertension in pregnant women affect perinatal outcomes?

In the study by Magee et al., the frequency of the primary outcome — pregnancy loss or high-level neonatal care for more than 48 hours — did not differ significantly between the groups. The primary-outcome rates were similar among 493 women assigned to less-tight control and 488 women assigned to tight control (31.4% and 30.7%, respectively; adjusted odds ratio, 1.02; 95% confidence interval [CI], 0.77 to 1.35). Most high-level neonatal care for more than 48 hours was related to complications of prematurity. There were no significant between-group differences with respect to other perinatal outcomes, including the proportion of newborns who were small for gestational age and the frequency of respiratory complications and treatment.

Table 2. Primary and Other Perinatal Outcomes.

Morning Report Questions

Q: How does tight control as compared to less-tight control of nonsevere, nonproteinuric hypertension in pregnant women affect serious maternal complications and other outcomes?

A: The frequency of the secondary outcome — serious complications (including death) — was also similar in the two groups. There were no maternal deaths. The most common maternal complication was the receipt of blood products. The frequency of abruption did not differ significantly between the groups. The gestational age at delivery and the frequency of cesarean delivery did not differ significantly between the groups.

Table 3. Secondary and Other Maternal Outcomes.

Q: Were there any significant between-group differences in this study?

A: Severe hypertension (equal to or greater than 160/110 mm Hg) developed in 40.6% of the women in the less-tight-control group and 27.5% of the women in the tight-control group (P<0.001).

Figure 2. Blood-Pressure Values among Women with Severe Hypertension.

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