January 28th, 2015

Tight Control of Hypertension During Pregnancy Tested

High blood pressure during pregnancy is increasingly common, largely due to older age and obesity. Although there is widespread agreement that hypertension in these women should be treated when it is high enough to raise the risk of stroke, there is little agreement about whether or how to treat mild hypertension.

In a study reported in the New England Journal of Medicine, investigators from Canada reported on 986 hypertensive pregnant women who had diastolic blood pressure of 90 to 105 mm Hg (or, for women already taking a blood pressure drug, 85 to 105 mm Hg). The women were randomized to less tight blood pressure control (target diastolic blood pressure, 100 mm Hg) or tight blood pressure control (target, 85 mm Hg). Three-quarters of the women had hypertension predating their pregnancy.

Blood pressure was 4.6 mm Hg lower in the tight group. However, there were no significant differences in the primary outcome of the trial, which was the loss of the pregnancy or the need for intense neonatal care in the 4 weeks after birth ( (31.4% in the less tight group versus 30.7% in the tight group).  Also, no significant differences in serious maternal complications were observed. However, severe hypertension occurred significantly more often in the less tight group than in the tight group (40.6% versus 27.5%, p < 0.001), although this was not accompanied by an increase in stroke or other serious complications.

In an accompanying editorial, Caren Solomon and Michael Greene write that the study “showed that tight control of hypertension conferred no apparent benefits to the fetus and only a moderate benefit (a lower rate of progression to severe hypertension) for the mother. It does, however, provide valuable reassurance that tight control, as targeted in this study, does not carry major risks for the fetus or newborn.”


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