Under the FDA's legacy pregnancy category labeling system, what category was amoxicillin classified as?

Amoxicillin (and most penicillins) were classified as FDA Pregnancy Category B under the older letter-based system — meaning animal studies showed no risk to the fetus, though adequate well-controlled human studies were lacking; they remain a preferred antibiotic choice in pregnancy when treatment is needed. Note that in 2015, the FDA replaced this letter system with the Pregnancy and Lactation Labeling Rule (PLLR), which provides narrative risk summaries instead of single-letter categories for newly labeled drugs, though many legacy drugs and exam questions still reference the older category system.