One of the most popular classifications of medications used throughout pregnancy are antibiotics. Many of the common drugs used by pregnant women such as penicillins, erythromycins, and cephalosporins have been considered safe with minimal risk of birth defects. However, with the creation of more resistant bacteria and the development of newer drug classifications, more choices have recently become available with less data and safety information available for use in pregnancy.
A recent study published by Crider, from the CDC’s National Center for Birth Defects and Developmental Disabilities, published in the Archives of Pediatric and Adolescent Medicine, November issue, discussed the association of birth defects found in pregnant women taking antibiotics anytime from one month before conception through the end of the first trimester.
The study involved 3,863 case mothers and 1,467 controls in a retrospective analysis that showed associations between exposure to certain antibiotics and birth defect outcomes. It did not attribute any causal relationship. In addition, the study was done by telephone interview approximately 6 weeks to 2 years after the pregnancy which could result in an inaccurate recall of medications.
Results showed confirmation of safety profiles for the commonly used penicillins, erythromycins, and cephalosporins. However, several other antibiotics commonly used in pregnancy to treat urinary tract infections, such as sulfonamides and nitrofurantoins, were associated with several birth defects. Among the defects for the nitrofurantoins (Macrobid) were anophthalmia or microphthalmos, hypoplastic left heart syndrome, atrial septa1 defects, and cleft lip with cleft palate. Associations with sulfonamides (Bactrim and Septra) were more numerous and included anencephaly, left sided heart defects, coarctation of the aorta, choanal atresia, transverse limb deficiency, and diaphragmatic hernia.
In conclusion, more data is needed to further analyze these associations of potential adverse effects on the fetus with the use of these medications. In the meantime it is always prudent to use the commonly prescribed medications as first line therapy where possible negative effects are almost nonexistent.
