The safety of prescription drugs in pregnancy is based on various factors that are specific to each woman. Many times, the safety of the drugs are uncertain, as studies done on animals may not reflect the same result in humans. Your doctor will use careful judgment to decide whether the benefits outweigh the risks. To assist doctors in deciding, the FDA created pregnancy letter categories to help describe the level of safety according to research. These categories are listed on drug labels, making it simple for doctors, nurses or pharmacists to evaluate the dangers. In addition, these professionals can obtain information from textbooks and research journals.
Category A Drugs
Category A drugs are those that have been studied in pregnant women and found to cause no ill effects. They are among the safest for use and can include folic acid, and levothyroxine (thyroid hormone medicine).
Category B Drugs
Category B drugs are described as those that have not been conclusive in human studies but show no ill effects when tested on pregnant animals. This category also indicates some problems resulted, but none in pregnant women's babies. Examples of these drugs include some antibiotics, such as amoxicillin, nausea medication (Zofran), medication for diabetes (Glucophage) and insulins for the treatment of diabetes (regular and NPH insulin).
Category C Drugs
Category C drugs represent those that are not well studied in humans and had some ill effects on animals. These drugs, however, may still be more useful than harmful. In addition, the research might also indicate a lack of appropriate research in both humans and animals. Examples include medicines for yeast infections (Diflucan) asthma medications (albuterol) and depression medications like Zoloft and Prozac.
Categogy D Drugs
Category D drugs are riskier medications that confirm some babies of pregnant women were born with problems related to the medication. Your doctor will decide if the risk is worth taking based on the need for the drug. Examples include depression medications (Paxil) seizure medications (Dilantin), certain chemotherapy drugs and bipolar drugs (lithium). In some cases, a mother may have side effects of a disorder that pose a greater danger to herself and her baby without medication and would likely be instructed to continue her medication throughout pregnancy.