Side Effects of Taking Prometrium During Pregnancy

Pregnant woman on couch

Progesterone supplements are given to pregnant women who have a history of low progesterone levels in pregnancy or a history of recurrent miscarriage. Progesterone is a hormone that helps maintains a pregnancy; normal levels are over 12 ng/ml in early pregnancy, with levels over 50 ng/ml by the end of the pregnancy. One form of progesterone prescribed for pregnant women is Prometrium, a pill taken several times a day.

Maternal Side Effects

Prometrium, like any drug, has side effects. Among the most common are drowsiness, nausea, cramping, abdominal pain, joint pain, bloating, breast tenderness, headache, depression and mood swings. These are also the main symptoms of pregnancy and are related to increased progesterone levels.

Less-common side effects, occurring less than 5 percent of the time in clinical trials, include viral infection, high blood pressure, deep vein thrombosis, vision changes, sleeping disorders and fever.

Fetal Side Effects

Prometrium and other forms of progesterone may increase the risk of hypospadias, an abnormal placement of the opening at the end of the penis, in male babies. Rare fetal complications include cases of cleft lip or palate and cardiac issues, such as ventricular septal defect or patent ductus arteriosis. While Prometrium should not be taken routinely in pregnancy, the risks outweigh the benefits in some situations that only your doctor can determine.

Prometrium is a category B drug for pregnancy, meaning that there are no controlled studies that show the drug to be harmful in pregnancy, according to the FDA pregnancy drug classifications reported by However, a 25-year study conducted by the Pope Paul VI Institute for the Study of Human Reproduction showed no increase in birth defects in more than 2,000 pregnancies studied.

Serious Side Effects

Because Prometrium increases fluid retention, women who have asthma, heart conditions, migraines, epilepsy or kidney problems should weigh the need for the drug carefully against the risks. Immediately report to your doctor any serious side effects, including any type of allergic reaction, such as difficulty breathing, palpitations, rash, hives or collapse. Women with allergy to peanuts should not take Prometrium.