Antibacterial Drugs and Pregnancy

There is no firm evidence that the penicillins, metronidazole, azithromycin, and clindamycin are teratogenic in humans; however, drugs in general should be prescribed with caution during pregnancy. To assist practitioners in prescribing drugs for the pregnant patient, the Food and Drug Administration (FDA) has established a code for categorizing drugs according to their potential to cause fetal injury.145

The penicillins, metronidazole, azithromycin, and clindamycin all have an FDA Pregnancy Category B rating, i.e., animal studies have revealed no evidence of harm to the fetus; however, there are no adequate and well-controlled studies in pregnant women.38,39,61,70,73,145 Since animal studies are not always predictive of a drug’s teratogenic effect in humans, antibacterial agents should only be prescribed during pregnancy if clearly indicated.38,39,61,70,73,145