Update on the use of antihypertensive drugs in pregnancy
Practice Guidelines as Topic
The use of antihypertensive agents in pregnancy for control of mild-to-moderate hypertension or for control of severe hypertension is summarized in Tables 2 and 3. Currently, there is little evidence to support the concept that BP control in pregnant women with chronic hypertension will prevent the subsequent occurrence of preeclampsia, itself the cause for most adverse outcomes in these patients. As BP falls in early pregnancy, decreasing or even discontinuing medication and monitoring is often possible in women with mild or moderate hypertension. Acknowledging limitations in evidenced-based data and other concerns discussed above regarding gestational age, we recommend a threshold for treatment of most pregnant hypertensive women of 140 to 150 mm Hg systolic, and/or 95 to 100 mm Hg diastolic to prevent worsening hypertension in the mother. Acceptable agents include methyldopa, labetalol, and nifedipine in standard doses. Atenolol use should probably be avoided in pregnancy, because it has been associated with slightly lower birth weights. ACE-Is and angiotensin receptor blockers should be avoided in all trimesters; when administered in the second and third trimesters, they are associated with a characteristic fetopathy, neonatal renal failure, and death, and, thus, are contraindicated. Recent data suggest that they should also be avoided in the first trimester. Finally, control of severe hypertension has been studied in a recent meta-analysis, and this suggests that intravenous labetalol or oral nifedipine is as effective as intravenous hydralazine, with fewer adverse effects. Many research questions surrounding hypertension in pregnancy and preeclampsia remain unanswered. Advancement of clinical knowledge requires studies that are large, collaborative, and multicentered. For example, to better understand the need for antihypertensive therapy in mild-tomoderate chronic hypertension, a study designed to detect a moderate (20%) relative risk reduction in preeclampsia or intrauterine growth restriction would require a randomized trial with enrollment of 1000 to 3000 women with chronic hypertension. Preconception management of hypertension, the necessity for antihypertensive agents, specific drug agents, racial differences, BP levels for initiation of therapy, and treatment targets all remain to be determined. Current guidelines rely only on evidence from small, largely underpowered trials and expert opinion. Finally, studies of antihypertensive medication in pregnancy often evaluate the effectiveness of a drug without examining fetal outcomes associated with harm; future studies must include detailed outcomes of risk and benefit for both the mother and baby. Better surveillance systems to routinely monitor adverse events and numbers of women exposed to particular agents are required to guide treatment efficacy, advance our knowledge of drug safety, and ultimately improve treatment options. © 2008 American Heart Association, Inc.
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