Methyldopa During Pregnancy: Safety and Evidence

What does the evidence say about methyldopa during pregnancy?

1. Methyldopa works by lowering the brain's signal to constrict blood vessels, and StatPearls describes it as having no teratogenic effects and remaining a second-line option that can be used safely during pregnancy. 1
2. In a Michigan Medicaid surveillance study of 242 infants exposed to methyldopa in the first trimester, 4.5 percent had a major birth defect, close to the expected background rate, which researchers said doesn't support a link between methyldopa and birth defects. 2
3. Methyldopa crosses the placenta and reaches concentrations in the fetus similar to the mother's blood levels, and one report described a small, temporary drop in newborns' blood pressure for the first two days after birth that wasn't considered clinically significant. 2
4. In a network meta-analysis of oral blood pressure medications in pregnancy, labetalol reduced the risk of severe hypertension and protein in the urine somewhat more than methyldopa, though the two medications were similar for other outcomes like preterm birth and fetal growth. 3
5. Because only small amounts of methyldopa pass into breast milk, estimated at less than 0.2 percent of the mother's weight-adjusted dose, no special precautions are recommended during breastfeeding, and no adverse effects were reported in a small group of breastfed infants studied. 4

Is methyldopa safe in each trimester?

• First trimester. A Michigan Medicaid surveillance study following 242 infants exposed to methyldopa in the first trimester found the rate of major birth defects matched what would normally be expected, one of the reasons it's had such a long track record in pregnancy.
• Second trimester. If methyldopa isn't fully controlling blood pressure, it's worth knowing that one large analysis found labetalol somewhat more effective at reducing severe hypertension and protein in the urine, information your provider can weigh alongside your specific numbers.
• Third trimester. Methyldopa crosses the placenta and has been linked to a small, temporary dip in a newborn's blood pressure for the first two days after birth, which research described as not clinically significant, so it's generally continued right up to delivery unless your provider advises otherwise.