Antibacterial Drugs and Pregnancy

The Food and Drug Administration (FDA) instituted a product labeling schema (A, B, C, D, X) in 1979, to categorize drugs according to their teratogenic risk to the fetus.148 The FDA issued a new rule on December 3, 2014, addressing pregnancy and lactation labeling information for prescription drug and biologic products.149 The new labeling requirement, to be phased in starting June 2015, replaces the letter categories with three detailed subsections that more accurately explain the real-world risks associated with a given drug exposure for a pregnant woman. (Table 6)
Table 6 - Pregnancy & Lactation Labeling Requirements of Prescription Drugs and Biological Products149
Subsection Requirement
Pregnancy • Information relevant to the use of the drug in pregnant women, such as dosing and potential risks to the developing fetus
• Information about whether there is a registry that collects and maintains data on how pregnant women are affected when they use the drug or biological product.
• Subheadings addressing: “risk summary”, “clinical considerations”, and “data”.
Lactation • Information about using the drug while breastfeeding, such as the amount of drug in breast milk and potential effects on the breastfed child.
• Subheadings addressing: “risk summary”, “clinical considerations”, and “data”.
Females and Males of Reproductive Potential • Information about pregnancy testing, contraception and about infertility as it relates to the drug.

There is no firm evidence that the penicillins, metronidazole, azithromycin, and clindamycin are teratogenic in humans. Animal studies have revealed no evidence of harm to the fetus; however, there are no adequate and well-controlled studies in pregnant women.34,37,61,70,77,149 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.34,37,61,70,77,149