What does FDA pregnancy category A indicate about a drug?

FDA pregnancy category A indicates that there is no risk to the fetus based on studies conducted with pregnant women. This category is the highest safety classification, meaning that adequate and well-controlled studies in pregnant women have not demonstrated any risk to the developing fetus in the first trimester and there is no evidence of risk in later trimesters. The overarching principle for categorizing a drug in this manner is the assurance that it has been shown to be safe for use during pregnancy without adverse effects on fetal development, making it the preferred choice when a medication is necessary for a pregnant individual.