Questions regarding medication and illicit drug use should human or animal studies of embryonic-fetal risk. These letbe part of routine preconceptional and prenatal care. Misinters also conveyed beneits of the given medication balanced formation is common. Individuals tend to underestimate the against its potential risks. The system, shown in Table 12-3, background risk for birth defects in the general population and was intended to simpliY risk-beneit data. exaggerate potential risks associated with medication exposure. Unfortunately, information regarding medication risk was In a recent population-based study of more than 270,000 births very oten incomplete and led to an overreliance on the deinifrom Utah that included 5500 fetuses and infants with major tion of the letter category alone. However, a higher letter grade birth defects, only 4 cases were attributed to medication expodid not necessarily mean greater risk, and drugs in the same catesure (see Fig. 12-1) (Feldkamp, 2017). And yet, Koren and gory oten had very diferent risks. Very few medications-fewer colleagues (1989) reported that a fourth of women exposed to than 1 percent-had demonstrated safety in human pregnancy nonteratogenic drugs thought they had a 25-percent risk for (category A), and most had no safety data in human or animal fetal anomalies. Misinformation may be amplified by inaccurate studies (category C). Another diiculty was that the classiication reports in the lay press. Knowledgeable counseling may allay system did not address inadvertent exposure, a common reason anxiety considerably and may even avert pregnancy termination. for counseling. Ultimately, it is the responsibility of the clinician
Several sources are available to assist providers with accurate to interpret letter category information in the context of mediand updated risk information. PubMed is a free tool from the cation dosage and route, timing of exposure during pregnancy, National Center for Biomedical Information that aids rapid other medications used, and underlying medical condition(s). search of published research. Online databases, such as Reprotox, To address these deiciencies, new labeling requirements were TERIS, and Shepard's Online Catalog of Teratogenic Agents, created and went into efect in 2015. Updates to older mediofer reviews of medication risks. hey summarize human and cations will be phased in over time (Food and Drug Adminanimal studies of teratogenicity and fetotoxicity, address the istration, 2014). With the new requirements, the FDA letter quality of the available evidence, and provide magnitude of risk. categories have been (or will be) removed from all prescription Lactmed, a database from the National Library of Medicine, drug and biological product labeling. he format for providing speciically deals with medication use by breastfeeding women. information includes a summary of risks, clinical considerations, Its entries on speciic medications describe levels in breast milk and available data. The pregnancy subsection has registry inforand potential efects on the infant. Finally, with recent changes mation, if available, as well as labor and delivery information. to the FDA labeling requirements, discussed next, the manufacFor each medication, a lactation subsection-formerly called turer's prescribing information has become increasingly helpful. "nursing mothers"-is included. There is also a section to address potential risks in females and males with reproductive potential .
• The Food and Drug Administration:
In 1979, the FDA developed a letter classiication system In addition to potential embryonic and fetal risks from drug in an efort to provide therapeutic guidance for prescribing exposure, counseling should discuss the risks and/or genetic
TABLE 12-3. Food and Drug Administration Letter Categories for Drugs and Medications (1•979-2015)a
Category A: Studies in pregnant women have not shown an increased risk for fetal abnormalities if administered during the first (second, third, or all) trimester(s) of pregnancy, and the possibility of fetal harm appears remote.