Background: Pregnancy induces multiple physiological, metabolic, and immunological alterations that increase susceptibility to infections, often necessitating antibiotic therapy. Evaluating the rational use of antibiotics among pregnant women is crucial for optimizing antimicrobial stewardship at the hospital level, improving clinical pharmacy services, and reducing the risk of antimicrobial resistance. Aim: To assess the rational use of antibiotics, including indication, selection, dosage, and treatment duration—among hospitalized pregnant women in the Department of High-Risk Pregnancy and the Department of Preterm Birth at the National Center for Maternal and Child Health. Materials and Methods: A retrospective study was conducted using a specifically designed data collection form to assess antibiotic use among inpatients at the National Center for Maternal and Child Health. Descriptive statistical analyses were performed using SPSS version 29.0. Results: A total of 348 pregnant inpatients were included, with a mean age of 31.6 ± 6.9 years. The mean length of hospital stay was significantly longer in the Department of Preterm Birth (12.5 ± 5.0 days) compared to the Department of High-Risk Pregnancy (5.9 ± 2.0 days; p < 0.001). The indications for antibiotic use were therapeutic in 39.1%, prophylactic in 33.0%, and unspecified in 21.3% of cases. The most frequently prescribed antibiotic regimen was a combination of β-lactams and metronidazole (29%). While the dosing of cefazolin and cefotaxime was largely appropriate, notable dosing discrepancies were observed in the dosing of ampicillin and azithromycin. Based on the U.S. FDA pregnancy risk classification, among a total of 762 antibiotic prescriptions, 87.0% belonged to category B, 8.8% to category C, and 4.2% to category D, with no significant variation across trimesters (p = 0.695). Conclusion The assessment of antibiotic use among hospitalized pregnant women at the National Center for Maternal and Child Health revealed that 39.1% of the prescriptions were therapeutic, 33.0% were prophylactic, and 21.3% lacked a clear indication for use. β-lactam antibiotics were the most commonly used agents, frequently combined with metronidazole. Based on the FDA classification system, 87% of the prescribed antibiotics belonged to category B, 8.8% to category C, and 4.2% to category D. These findings indicate inappropriate antibiotic use and insufficient implementation of antimicrobial susceptibility testing. Therefore, strict adherence to antibiotic stewardship programs and strengthening of clinical pharmacy services are necessary to improve antibiotic use practices.