The “July effect” is a widely held, yet poorly studied, belief that the quality of care delivered in teaching hospitals decreases during the summer months due to the arrival of new trainee physicians. Using national inpatient stay data from 2018, this study found that the risk of postpartum hemorrhage among patients treated at teaching hospitals was significantly higher during the first six months of the academic year (July to December) compared to the second half (January to June). The authors recommend future research examine whether postpartum hemorrhage is associated with resident work hours, technical deficiencies, or unfamiliarity with hospital practices, and emphasize the importance of monitoring and clinical training to mitigate the impacts of the “July effect.”