Sulfonamides and nitrofurantoins were associated with birth defects.
Antibacterial drugs are among the most commonly used medications during pregnancy. Investigators analyzed data from a national birth defects study to compare antibiotic use in 13,155 mothers of infants with at least one major birth defect and 4941 randomly selected mothers of infants without birth defects from the same geographic region and born during the same period (1997–2003). Antibiotic use was determined by telephone interview 6 weeks to 2 years after the pregnancy. Exposure to antibiotics was defined as reported use during the month before the estimated date of conception through the end of the first trimester; 14% of cases and 13% of controls used antibiotics during this interval.
Sulfonamides were associated with six major birth defects, including anencephaly (odds ratio, 3.4) and hypoplastic left heart syndrome (OR, 3.2). Nitrofurantoins were associated with four birth defects (including hypoplastic left heart syndrome; OR, 4.2), and erythromycins were associated with two defects. Penicillins, cephalosporins, and quinolones each were associated with one defect.
Comment: The authors note the limitations of this retrospective study, including the major limitation that causality cannot be determined. However, the results are reassuring. Penicillins, erythromycins, and cephalosporins appear to be safe. Sulfonamides and nitrofurantoins appear to be associated with several birth defects and should be avoided if possible. Quinolones, used infrequently by women in this study, are not recommended for use during pregnancy.
— Howard Bauchner, MD Published in Journal Watch Pediatrics and Adolescent Medicine November 18, 2009
Sulfonamide is the basis of several groups of drugs. The original antibacterial sulfonamides (sometimes called simply sulfa drugs) are synthetic antimicrobial agents that contain the sulfonamidegroup. Some sulfonamides are also devoid of antibacterial activity, e.g., the anticonvulsant sultiame. The sulfonylureas and thiazide diuretics are newer drug groups based on the antibacterial sulfonamides.
Sulfa allergies are common, hence medications containing sulfonamides are prescribed carefully. It is important to make a distinction between sulfa drugs and other sulfur-containing drugs and additives, such as sulfates and sulfites, which are chemically unrelated to the sulfonamide group, and do not cause the same hypersensitivity reactions seen in the sulfonamides.