Drugs in Pregnancy

Do the Benefits Outweigh the Risks?

Anita T. Mosley, PhD, PharmD; Amy P. Witte, PharmD


US Pharmacist. 2013;38(9):43-46. 

In This Article

Do the Benefits Outweigh the Risks?

Drug use during pregnancy continues to remain a major concern due to the unknown effects on mother and fetus. Physicians are faced with difficult situations as they have very little information to help them decide whether the potential benefits to the mother outweigh the risks to the unborn fetus. To help guide physicians in their selection and interpretation of the risks associated with the drug, the FDA introduced a drug classification system in 1979 (Table 1).[4–7] Most information provided in this classification is derived from animal studies and uncontrolled studies in humans such as postmarketing surveillance reports. To date, very few well-controlled studies have been conducted in pregnant women, most likely due to ethical considerations. Two important limitations of the classification include:[5–7]

  • All new FDA-approved medications are classified as Category C

  • There are no FDA regulations requiring further studies or seeking more data; therefore, changes in the classification are rare. In addition, the classification is often not changed when new data become available.

Approximately 20 to 30 of the most commonly used drugs are identified as teratogens, with 7% of the more than 1,000 medications listed in the Physicians' Desk Reference classified as Category X.[7] Some of the commonly used drugs with proven teratogenic effects in humans are warfarin, isotretinoin, valproic acid, and tetracycline antibiotics. The timing of fetal exposure to a drug is critical to the likelihood of an adverse effect occurring. Most of the major body structures are formed during the first trimester, and exposure during this time could lead to structural teratogenic effects.[8] Some drugs have different FDA categorizations based on the trimester of pregnancy.

As pharmacists, we play a vital role in educating and counseling pregnant women on the risks associated with a drug. Informing a pregnant woman of the risks and possible fetal defects can reduce the number of complications. Furthermore, it is our responsibility to ensure that other health care professionals are familiar with the current literature available on the safety of drugs administered during pregnancy. This article will present a concise discussion of common medications used to treat pregnancy-associated conditions, including cough, cold, and allergies; pain; and gastrointestinal (GI) disorders; as well as provide an update on the current immunization recommendations for pregnancy.