15% of hypertensive women on meds have poor pregnancy outcomes

Despite normal baseline blood pressures without medications before 20 weeks of gestation, pregnant women with chronic hypertension are at an increased risk of poor outcomes compared with women without, according to new research published in the May issue of Obstetrics & Gynecology.

“Little is known about this particular subgroup of pregnancies complicated by chronic hypertension; the majority of prior studies of chronic hypertension in pregnancy use only diagnostic codes or medication lists to assess the risks associated with chronic hypertension,” wrote Lorie M. Harper, MD, MSCI, of the University of Alabama at Birmingham, and colleagues. “Whether women with a history of chronic hypertension but who remain normotensive without medication during pregnancy are at increased risk for stillbirth, fetal growth restriction, or other adverse perinatal outcomes during pregnancy is not clear.”

Harper et al. sought to compare pregnancy outcomes of women with normal blood pressure levels (control group) and women with a history of chronic hypertension with normal blood pressure before 20 weeks of gestation. They stratified the latter group by whether they were receiving antihypertensive medication.

Researchers found that women who were taking antihypertensive medications and those not taking medications but exhibiting hypertension had three-times the risk for still births and neonatal deaths, among other negative outcomes.

The composite primary outcome occurred among almost 10 percent of women with a hypertension history but not taking antihypertensive drugs, in almost 15 percent of women who were taking antihypertensive drugs, and in almost 3 percent of women with no history of hypertension.  

Additionally, secondary outcomes included preeclampsia, preterm births, and infants small for gestational age—though those outcomes were not statistically significant.

The analysis included 830 women. Of the cohort, 26 percent had blood pressure less than 140/90 mmHg and did not receive antihypertensive medication and 74 percent had blood pressure less than 140/90 mmHg but were receiving antihypertensive medication before the 20-week gestation mark. This group was compared to 476 women who did not exhibit chronic hypertension.

Women with hypertension were more likely to be older and have baseline renal disease and diabetes compared with those in the control group.

Part of the cohort taking antihypertensive medications had an increased risk for preeclampsia, severe preeclampsia, preterm birth and a smaller sized infant for gestational age. Women with a history of hypertension but not taking medications did not have an increased risk.

The researchers said women with hypertension were more likely to be older and have baseline renal disease and diabetes compared to women in the control group (no hypertension).

The authors noted one of the limitations of this study was that the sample was from a single academic institution and therefore may not be generalizable to other institutions. Specifically, the demographic of the group was largely black, obese and had high incidences of pre-gestational diabetes.