Pregnancy: Nifedipine is contraindicated in pregnancy before week 20 (see Contraindications). There are no adequate and well controlled studies in pregnant women.
In animal studies nifedipine has been shown to produce embryotoxicity, fetotoxicity and teratogenicity (see Pharmacology: Toxicology: Preclinical safety data under Actions).
Lactation: Nifedipine passes into the breast milk. As there is no experience of possible effects on infants, breastfeeding should first be stopped if nifedipine treatment becomes necessary during the breastfeeding period.
In-vitro fertilization: In single cases of in vitro fertilization calcium antagonists like nifedipine have been associated with reversible biochemical changes in the spermatozoa's head section that may result in impaired sperm function. In those men who are repeatedly unsuccessful in fathering a child by in vitro fertilization, and where no other explanation can be found, calcium antagonists like nifedipine should be considered as possible causes.