The safety of taking nifedipine in pregnancy is not fully known. This is classified as a pregnancy category C drug, which indicates there is reason to suspect possible safety issues. Animal testing has shown an increase in the rate of miscarriage and birth defects after being given high doses of nifedipine. The few human studies that have been performed, however, have shown no ill effects to the fetus. A woman may take nifedipine in pregnancy if she and her doctor believe that the benefits outweigh the risks.
Nifedipine is a calcium-channel blocker, which means it affects the amount of calcium in the heart muscle to relax the blood vessels. It is used to treat high blood pressure and other forms of heart disease. Sometimes it is used to stop preterm labor, although as of 2011 it was not approved by the United States Food and Drug Administration (FDA) for this use. Side effects include
High blood pressure may be present before pregnancy or occur as a result. If it occurs during pregnancy, it may be a sign of preeclampsia, a dangerous condition that can result in seizures or a stroke. The cure for preeclampsia is the delivery of the baby. If high blood pressure was present before pregnancy, delivering the baby won't usually have an effect on the condition one way or the other. Nifedipine in pregnancy may be used to treat high blood pressure regardless of whether it is related to the pregnancy.
Untreated high blood pressure in pregnancy can be dangerous for both mother and baby. Pregnant women have a higher risk for blood clots, which can cause a heart attack, stroke, or pulmonary embolism. These can happen even more easily in women with high blood pressure. High blood pressure increases the risk for placental abruption, in which the placenta detaches prematurely from the uterus causing hemorrhage and possible stillbirth. The baby gets less blood and oxygen when the mother has high blood pressure, which can lead to growth problems or fetal death.
It is important to treat high blood pressure. Women who do not wish to take nifedipine in pregnancy may ask their doctors about other treatment options. There are other classes of drugs, such as beta blockers, some of which are considered very safe during pregnancy. Since they work in a different way than nifedipine, they may not be suitable for everyone. Diet modifications and exercise may also control blood pressure for some women.
Women who do wish to take nifedipine in pregnancy but are worried about birth defects may find other treatment methods for the first trimester. After the first trimester is complete, the risks of birth defects is reduced significantly. The risks of high blood pressure affecting the mother or baby, however, increase as the pregnancy progresses.