Medicine for preeclampsia and high blood pressure during pregnancy may be used to:

• Control high blood pressure. Lowering high blood pressure does not prevent preeclampsia from getting worse, because high blood pressure is only a symptom of the condition, not a cause. High blood pressure medicine is usually not used unless a pregnant woman's diastolic blood pressure (the second number) reaches levels of about 105 mm Hg (millimeters of mercury) and above.¹ Expectant management is the preferred treatment for mild high blood pressure during pregnancy.
• Prevent seizures. Magnesium sulfate is usually started before delivery and continued for 24 hours after delivery for women with pregnancy-related seizures (eclampsia) and those with moderate to severe preeclampsia.
• Speed up fetal lung development. When possible, a corticosteroid (betamethasone or dexamethasone) is given to the mother prior to a premature birth (up to 34 weeks of gestation). This medicine matures the fetus's lungs over a 24-hour period, which lowers the risk of breathing problems after birth.

After childbirth: Taking high blood pressure medicine while breast-feeding

There are several commonly used high blood pressure medicines that have no reported effects on the breast-feeding baby. These medicines include labetalol and propranolol, which are most commonly recommended, as well as hydralazine and methyldopa. Nadolol, metoprolol, and nifedipine are detectable in mothers' milk, but they have no known effects on the breast-feeding baby.¹⁸

Medication Choices

High blood pressure medicines commonly used during pregnancy include:

• Methyldopa (a first-choice oral medicine for controlling high blood pressure during a pregnancy).
• Hydralazine (a first- or second-choice intravenous medicine for quickly lowering severely high blood pressure during pregnancy).
• Labetalol (a first- or second-choice intravenous medicine for quickly lowering severely high blood pressure in the hospital, and also considered a first- or second-choice oral medicine for controlling high blood pressure during pregnancy).
• Nifedipine (a first- or second-choice oral medicine for controlling high blood pressure during pregnancy).

Magnesium sulfate is considered the safest and most effective anticonvulsant for preventing eclampsia (seizures) during pregnancy.⁹

Antenatal corticosteroid medicines include betamethasone and dexamethasone. Research suggests that corticosteroids are the single most effective treatment for preventing complications in preterm newborns.²⁷

What To Think About

There is currently not enough medical evidence to show which high blood pressure medicine is most effective for use during pregnancy. But it does seem clear that 2 drugs-diazoxide and ketaserin-are the least reliable for use during pregnancy.²⁸ Although the above-mentioned medicines are widely used, further large studies are needed.

Some high blood pressure medicines are dangerous during pregnancy. ¹⁷ If you take high blood pressure medicines, talk to your health professional about the safety of your medicine before you become pregnant or as soon as you learn you are pregnant. Make sure that your health professional has a complete list of all medicines that you are taking.

Lowering blood pressure too much or too fast can reduce blood flow to the placenta, causing problems for the fetus. Medicine is therefore reserved for preventing severely high blood pressure levels that are potentially life-threatening to you or your fetus.