What is Known: • Antibiotic application during the perinatal period is unavoidable in the clinic. • Misuse of antibiotics can cause various unintended consequences, especially for antibiotic resistance.

What is New: • Antibiotic treatments had no influence on the microbiota of breast milk but greatly disturbed the gut microbiota composition in infants. • The gut microbiota in infants would partly return to its initial state after rehabilitation but the transfer of ARGs would leave the hidden trouble of antibiotic resistance.