A total of 164 new diagnoses (5.6%) of lower range stage 1 hypertension were made when the revised American Heart Association and the American College of Cardiology (ACC-AHA) Task Force on Clinical Practice Guidelines for chronic hypertension in adults were applied to a population of 2,947 pregnant women.
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These patients had a significantly increased risk of preeclampsia as well as an increased risk of gestational diabetes mellitus and preterm birth, compared with normotensive patients, according to a study published in Obstetrics & Gynecology.
Elizabeth F. Sutton, PhD, and her associates at Magee-Womens Research Institute in Pittsburgh, used data from a Eunice Kennedy Shriver National Institute of Child Health and Human Development study. It included 2,947 pregnant women with singleton pregnancies where 94% of women were normotensive prior to 25 weeks of gestation. The researchers identified 164 new cases (6%) of lower range stage 1 hypertension under the ACC-AHA guidelines. Patients were then randomized to receive 60 mg of aspirin (1,399 normotensive patients, 66 stage 1 hypertension patients) or placebo (1,384 normotensive patients, 98 stage 1 hypertension patients).
The women had their blood pressure (BP) measured at 25 weeks of gestation or prior, and those patients with a systolic BP between 130 mm Hg and 139 mm Hg or diastolic BP between 80 mm and 89 mm were reclassified as having stage 1 hypertension under the new ACC-AHA guidelines; outcomes were compared with normotensive women with a systolic BP of 130 mm Hg and diastolic BP of 80 mm Hg. The researchers also performed a sensitivity analysis that restricted enrollment to 1,661 women who were at 20 weeks of gestation or prior, they said.
“Of important note, as a result of eligibility criterion excluding women with chronic hypertension (greater than 135/85 mm Hg) at enrollment, the enrollment BP range within the stage 1 hypertension group was limited to lower range stage 1 hypertension, that is, 130-135, 80-85 mm Hg, or both,” Dr. Sutton and her colleagues wrote.
The researchers found a significantly increased risk of preeclampsia among hypertensive pregnant women in the placebo group (15%) compared with normotensive (5%) women (relative risk, 2.66; 95% confidence interval, 1.56-4.54; P less than .01). These patients also had an increased risk of gestational diabetes mellitus (6%) compared with normotensive (2.5%; P = .03) pregnant women as well as an increased risk of preterm birth (4% vs. 1%; P = .01). Among women with stage 1 hypertension who received low-dose aspirin, there were no significant differences regarding the rate of preeclampsia, gestational diabetes mellitus, or preterm birth risk.
“Although prepregnancy BPs would be ideal for diagnosis, prior studies have shown that women do not consistently seek primary care outside of pregnancy,” Dr. Sutton and her colleagues wrote. “In the United States, preconception care engagement rates are between 18% and 45% in reproductive-aged women; thus, early pregnancy BPs may be all that is available for the obstetrician.”
Limitations to the secondary analysis included the original study’s exclusion of BPs higher than 135/85 mm Hg and the small sample size of patients who met the new criteria for stage 1 hypertension. The researchers also noted an increased risk of preeclampsia among patients with intake systolic BP between 120 mm Hg and 129 mm Hg, “with a smaller magnitude of risk compared with stage 1 hypertension.
“These findings suggest preliminarily that when considering preeclampsia risk based on early pregnancy BP, perhaps BP could be considered as a continuous variable rather than categorical,” Dr. Sutton and her colleagues noted.
This study was supported in part by the American Heart Association and the Eunice Kennedy Shriver NICHD. The authors reported no relevant financial conflicts of interest.
SOURCE: Sutton EF et al. Obstet Gynecol. 2018 Oct doi: 10.1097/AOG.0000000000002870.