Perinatal Outcomes in Women With a History of Chronic Hypertension but Normal Blood Pressures Before 20 Weeks of Gestation

OBJECTIVE: To compare the perinatal outcomes of normotensive women with those of women with a history of chronic hypertension with normal blood pressures before 20 weeks of gestation, stratifying the latter by whether they were receiving antihypertensive medication. METHODS: We conducted a retrospective cohort study of all singletons with a history of chronic hypertension from 2000 to 2014. Exclusions were blood pressure greater than 140/90 mm Hg before 20 weeks of gestation, fetal anomalies, major medical problems other than hypertension, and diabetes. For the same time period, a randomly selected group without a diagnosis of chronic hypertension was chosen using the same exclusion criteria. Outcomes were compared among women without chronic hypertension, women with chronic hypertension on no antihypertensive medication but with blood pressures less than 140/90 mm Hg before 20 weeks of gestation, and women with chronic hypertension on antihypertensive medication with blood pressures less than 140/90 mm Hg before 20 weeks of gestation. The primary outcome was a perinatal composite of stillbirth, neonatal death, respiratory support at birth, arterial cord pH less than 7, 5-minute Apgar score 3 or less, and seizures. Secondary outcomes assessed were preterm birth before 37 and 34 weeks of gestation, small for gestational age, and preeclampsia. RESULTS: Of 830 women with chronic hypertension and blood pressures less than 140/90 mm Hg before 20 weeks of gestation, 212 (26%) were not taking antihypertensive medication and 618 (74%) were. These groups were compared with 476 women without chronic hypertension. Women with hypertension were more likely to be older and have baseline renal disease and diabetes compared with women in the no hypertension group. The perinatal composite was more common in both hypertensive groups: no antihypertensive medication (9.9%) and antihypertensive medication (14.6%) compared with women in the control group (2.9%) (adjusted odds ratio [OR] 2.9, 95% CI 1.21-6.85 no antihypertensive medications compared with no chronic hypertension; adjusted OR 5.0, 95% CI 2.38-10.54 antihypertensive medications vs no chronic hypertension). The risk of early preterm birth, small for gestational age, and preeclampsia was not significantly increased in women with chronic hypertension and no antihypertensive medications compared with women without chronic hypertension. CONCLUSION: Despite normal baseline blood pressures without medications before 20 weeks of gestation, women with chronic hypertension are at an increased risk of adverse perinatal outcomes compared with women without.