From the FDA Drug Label
Pregnancy Category C In rodents, rabbits and monkeys, nifedipine has been shown to have a variety of embryotoxic, placentotoxic, teratogenic and fetotoxic effects... There are no adequate and well-controlled studies in pregnant women.
- Pregnancy use: The FDA drug label does not provide a specific duration for the safe use of nifedipine in pregnancy.
- Key considerations:
- Nifedipine has been shown to have embryotoxic, placentotoxic, teratogenic, and fetotoxic effects in animal studies.
- Careful monitoring of blood pressure is necessary when administering nifedipine in combination with IV magnesium sulfate in pregnant women.
- There are no adequate and well-controlled studies in pregnant women. The FDA drug label does not answer the question.
From the Research
Nifedipine can be used throughout pregnancy when medically necessary, with no established maximum duration limit, as it is generally considered safe for both short-term and long-term use during pregnancy. The decision to use nifedipine in pregnancy should be based on the individual patient's needs and medical condition, such as hypertension or preterm labor. According to a systematic review and network meta-analysis published in 2019 1, nifedipine is one of the recommended first-line treatments for severe hypertension in pregnancy, and it has been found to be superior to hydralazine in achieving successful treatment of severe hypertension.
The use of nifedipine in pregnancy has been studied in several trials, including a randomized clinical trial published in 2019 2, which compared the efficacy and safety of nifedipine with methyldopa and no medication in women with mild to moderate chronic hypertension. The results showed that antihypertensive drug therapy, including nifedipine, is advisable in mild to moderate chronic hypertension during pregnancy to decrease maternal and fetal morbidity.
Some key points to consider when using nifedipine in pregnancy include:
- The immediate-release formulation is typically used for acute blood pressure management at doses of 10-20 mg
- Extended-release versions (30-90 mg daily) are preferred for ongoing treatment
- For preterm labor tocolysis, nifedipine may be used for 48-72 hours to allow for steroid administration
- Nifedipine works by blocking calcium channels, relaxing smooth muscle in blood vessels and the uterus, which lowers blood pressure and reduces uterine contractions
- Common side effects include headache, flushing, and dizziness
- Blood pressure should be monitored regularly during treatment, and dosage adjustments may be needed as pregnancy progresses due to physiological changes in maternal blood volume and metabolism.
Overall, the available evidence suggests that nifedipine is a safe and effective treatment option for hypertension and preterm labor in pregnancy, and it can be used for as long as medically necessary, with no established maximum duration limit 1, 2.