Severe hypertension in pregnancy can occur in women with chronic hypertension, or can indicate gestational hypertension or pre-eclampsia. Hypertension is a strong risk factor for stroke, coronary heart disease, congestive heart failure, kidney disease and death, and lowering blood pressure (BP) prevents these complications in nonpregnant women. Typically these complications develop over many years, and the treatment of mild chronic hypertension in pregnancy remains controversial. With severe hypertension, the goal of therapy in pregnancy—as in the nonpregnant woman—is focused on preventing acute complications, such as stroke. In pregnancy, however, acute lowering of BP raises concerns of changes to maternal haemodynamics with resultant reduction of uteroplacental perfusion. In addition, there are concerns about the safety of medications that cross the placenta and may harm the fetus. These unique concerns change the therapeutic options for the pregnant woman.
In recent guidelines, the American College of Obstetricians and Gynecologists (American College of Obstetricians and Gynecologists; Task Force on Hypertension in Pregnancy. Obstet Gynecol 2013;122:1122–31) suggests that parenteral labetalol or hydralazine, or oral nifedipine, are reasonable first-line agents for acute lowering of BP in the hospital setting. The authors indicate that the choice and route of administration should be based primarily on the physician's familiarity and experience, as well as specific clinical circumstances such as contraindications to a particular agent. The 2010 UK National Institute for Health and Clinical Excellence (NICE) Hypertension in Pregnancy guidelines also recommend nifedipine or labetalol for treatment of severe hypertension in pregnancy or postpartum (NICE. Hypertension: clinical management of primary hypertension in adults [update]. 2011. http://guidance.nice.org.uk/CG127).
In this systematic review, the authors reviewed the literature on use of oral antihypertensive therapy for treatment of severe pregnancy-related hypertension. They focused their review on randomised controlled trials of oral (or sublingual) agents, including nifedipine, labetalol and methyldopa. The authors acknowledge that the data on which they based their review are limited; the studies that have been done were generally small and of fair quality at best. However, the finding that short-acting nifedipine compared favourably with intravenous hydralazine or labetalol as to achievement of target BP, and maternal and perinatal outcomes, is certainly reassuring. Most (84%) achieved the target BP, half with just one dose. Maternal hypotension was uncommon (1.6%). The authors also reviewed studies using oral labetalol and methyldopa; these achieved the target BP less often (47% and 56%, respectively) although there were no studies directly comparing these other agents to nifedipine.
The finding that a single oral agent can adequately and safely lower BP in the pregnant woman with severe hypertension is important. There are many benefits to oral agents, including the ability to use them in the outpatient setting, where such severe hypertension is often detected, or in limited resource settings. In clinical settings in which transport to an inpatient facility may occur only after lengthy delays, the ability to quickly administer an efficacious agent can greatly improve outcomes for both mother and fetus.
Disclosure of interests
I have no relevant conflicts of interest to disclose.