Use of macrolide antibiotics during pregnancy increases risk of birth defects. A recent study in the February 19 BMJ compared children of mothers who took the macrolide antibiotics erythromycin, clarithromycin, or azithromycin during pregnancy to children whose mothers took penicillin. The results showed an increased risk of major malformations in children whose mothers took macrolides during the first trimester (27.65 versus 17.65 per 1,000 live births), particularly cardiovascular malformations, and an increased risk of genital malformations when mothers took macrolides at any time during pregnancy (4.75 versus 3.07 per 1,000 live births). The researchers concluded that, pending further research, macrolides should be used with caution during pregnancy and alternative antibiotics be used in the meantime.