Nifedipine and Pregnancy
In animal studies on nifedipine and pregnancy, the drug was shown to increase the risk of miscarriages and birth defects, such as cleft palate and problems with limbs. However, animals do not always respond to drugs in the same way as humans. Therefore, if you are taking nifedipine and pregnancy occurs, your healthcare provider will consider the benefits and risks in your particular situation.
Nifedipine may not be safe for women to take when pregnant. This conclusion is based on animal studies that looked at the effects of nifedipine during pregnancy.
The U.S. Food and Drug Administration (FDA) uses a category system to classify the possible risks to a fetus when a specific medicine is taken during pregnancy. Pregnancy Category C is given to medicines that have not been studied in pregnant humans but that do appear to cause harm to the fetus in animal studies. Also, medicines that have not been studied in any pregnant women or animals are automatically given a pregnancy Category C rating.
Nifedipine was given a pregnancy Category C rating because of potential problems in animal studies. When given to pregnant rabbits, mice, and rats, nifedipine caused increased miscarriages and birth defects. These birth defects included problems with fingers or toes, rib deformities, and cleft palate.
However, it is important to note that animals do not always respond to medicines the same way that humans do. Therefore, a pregnancy Category C medicine may be given to a pregnant woman if her healthcare provider believes that the benefits to the woman outweigh any risks to the unborn child.
Nifedipine is sometimes used to stop preterm labor, especially when other medications have failed. It helps to relax the smooth muscle of the uterus, stopping premature labor. Since nifedipine is not approved for preterm labor, however, this is considered an "off-label" use.