BACKGROUND: Overuse of antibiotics is a major challenge and undermines measures to control drug resistance worldwide. Postnatal women and newborns are at risk of infections and are often prescribed prophylactic antibiotics although there is no evidence to support their universal use in either group. METHODS: We performed point prevalence surveys in three hospitals in Dar es Salaam, Tanzania, in 2018 to collect descriptive data on antibiotic use and infections, in maternity and neonatal wards. RESULTS: Prescribing of antibiotics was high in all three hospitals ranging from 90% (43/48) to 100% (34/34) in women after cesarean section, from 1.4% (1/73) to 63% (30/48) in women after vaginal delivery, and from 89% (76/85) to 100% (77/77) in neonates. The most common reason for prescribing antibiotics was medical prophylaxis in both maternity and neonatal wards. CONCLUSIONS: We observed substantial overuse of antibiotics in postnatal women and newborns. This calls for urgent antibiotic stewardship programs in Tanzanian hospitals to curb this inappropriate use and limit the spread of antimicrobial resistance.