Chlorothiazide and Pregnancy
Some studies on chlorothiazide and pregnancy have shown that the drug may cause birth defects or other problems in a developing fetus. If you are taking chlorothiazide and pregnancy occurs, your healthcare provider will weigh the benefits and risks before making a recommendation for your situation.
Chlorothiazide (Diuril®) is a pregnancy Category C medicine, meaning that it may not be safe to use during pregnancy.
The U.S. Food and Drug Administration (FDA) uses a pregnancy 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 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.
In animal studies, chlorothiazide did not appear to cause any problems. Human studies show conflicting results. Some studies have shown that taking chlorothiazide early in pregnancy does not cause birth defects, while other studies have suggested a link between chlorothiazide and birth defects. Chlorothiazide can cause electrolyte imbalance, low blood sugar (hypoglycemia), and other problems in a fetus. When taken later in pregnancy, chlorothiazide may slow the progression of labor (since it has an effect on the uterine muscles).
In general, diuretics (including chlorothiazide) should not be used to treat high blood pressure during pregnancy (gestational hypertension). Chlorothiazide should not be used to treat fluid retention caused by pregnancy, but can be used in pregnant women to treat fluid retention due to other medical problems, such as kidney failure.