The latest article in our Clinical Practice review series, Chronic Hypertension in Pregnancy, reviews the potential risks associated with pregnancy among women with chronic hypertension and recommended treatment before and during pregnancy. Current recommendations regarding medications are reviewed.
The prevalence of chronic hypertension in pregnancy in the United States is estimated to be as high as 3%, which represents a substantial increase over time. This increase in prevalence is primarily attributable to the increased prevalence of obesity, a major risk factor for hypertension, as well as the delay in childbearing to ages when chronic hypertension is more common.
• What are the risks associated with chronic hypertension in pregnancy?
Women with chronic hypertension have an increased frequency of preeclampsia (17 to 25% vs. 3 to 5% in the general population), as well as placental abruption, fetal growth restriction, preterm birth, and cesarean section. Preeclampsia is a leading cause of preterm birth and cesarean delivery in this population.
• How does the blood pressure of women with chronic hypertension change during pregnancy?
Most women with chronic hypertension have a decrease in blood pressure during pregnancy, similar to that observed in normotensive women; blood pressure falls toward the end of the first trimester and rises toward prepregnancy values during the third trimester. As a result, antihypertensive medications can often be tapered during pregnancy.
Morning Report Questions
Q: What blood pressure targets are generally recommended during pregnancy?
A: Various professional guidelines provide disparate recommendations regarding indications for starting therapy (ranging from a blood pressure >159/89 mm Hg to >169/109 mm Hg) and for blood-pressure targets for women who are receiving therapy (ranging from <140/90 mm Hg to <160/110 mm Hg). For women whose antihypertensive therapy is continued, aggressive lowering of blood pressure should be avoided, though prospective controlled trials to support these recommendations are not available.
Q: What medications are recommended to manage hypertension in pregnancy?
A: The antihypertensive agent with the largest quantity of data regarding fetal safety is methyldopa, which has been used during pregnancy since the 1960s. Labetalol, a combined alpha- and beta-receptor blocker, is often recommended as another first-line or second-line therapy for hypertension in pregnancy. Long-acting calcium-channel blockers also appear to be safe in pregnancy, although experience is more limited than with labetalol. Angiotensin-converting-enzyme inhibitors and angiotensin-receptor blockers are contraindicated in pregnancy.