From the Guidelines
Pregnancy Category C indicates that animal studies have revealed adverse effects on the fetus and there are no controlled studies in women, or studies in women and animals are not available, and drugs should be given only if potential benefits justify the potential risk to the fetus. This classification is part of the US Food and Drug Administration system, which categorizes drugs from A (safest) to X (known danger—do not use!) based on their safety during pregnancy and breastfeeding 1. The key characteristics of Category C medications are:
- Animal reproduction studies have shown adverse effects on the fetus
- There are no controlled studies in pregnant women
- The potential benefits of the drug may justify the potential risk to the fetus Some examples of Category C medications include certain antidepressants, antibiotics, and anticonvulsants. When prescribing these medications to pregnant women, healthcare providers must carefully weigh the benefits against risks, considering factors such as the severity of the mother's condition, available alternative treatments, and the stage of pregnancy 1. It's worth noting that the FDA has replaced this categorization system with the Pregnancy and Lactation Labeling Rule (PLLR), which provides more detailed information about risks, but many clinicians and resources still reference the older category system when discussing medication safety in pregnancy. In clinical practice, the use of Category C medications during pregnancy requires careful consideration of the potential risks and benefits, and alternative treatments should be considered whenever possible 1.
From the Research
Pregnancy Category C
Pregnancy Category C indicates that information regarding the risk to the fetus is unknown 2. This classification is given to the vast majority of drugs, as pregnant women are not included in drug studies for ethical reasons. As a result, most decisions regarding the safety of a particular drug are based on:
- Animal studies
- Available case reports
- Theoretical information based on pharmacokinetic properties 2
Determining Fetal Safety
The development of Pregnancy Registries has allowed for the collection, analysis, and availability of more information regarding the safety of drugs during pregnancy 2. This information assists healthcare providers in selecting optimal therapy for women seeking pregnancy or those already pregnant. Key points to consider when determining fetal safety include: