In general, most cardiovascular medications may be used during pregnancy. Digoxin crosses the placenta but has not been shown to be teratogenic, although levels must be carefully monitored to avoid toxicity. Serum levels generally fall during pregnancy.
Diuretics cross the placenta but are not teratogenic. Because of their potential effects on uteroplacental perfusion, they are usually not used to treat pregnancy-induced hypertension but may be continued during pregnancy in a woman who is taking them chronically.
Antiarrhythmic agents, such as procainamide and quinidine, have not been shown to be harmful to the fetus. Although concerns about intrauterine growth restriction exist, beta-blockers may also be used if indicated. Experience with newer antiarrhythmics (flecainide, mexiletine, amiodarone) is limited, but so far, no adverse effects have been reported.
Calcium channel blockers are gaining in use during pregnancy and may be used when necessary. These agents cross the placenta and have been used to treat fetal tachycardia in utero.
Angiotensin-converting enzyme inhibitors should be avoided during pregnancy because of reports of fetal loss in animals and because of case reports in humans of anuric renal failure, sometimes fatal, seen in neonates exposed in utero.