Don't go to the hospital in July? Not true in obstetrics

Each year, teaching hospitals across the United States experience an influx of new medical residents starting on July 1st, while the previous year's residents advance to higher levels of postgraduate education. This phenomenon, known as the "July Effect," refers to the theoretical increase in adverse patient outcomes due to inexperienced resident physicians assuming more independent roles in patient care.

To assess severe maternal morbidity (SMM) and maternal mortality risk across different quarters of the academic year.

This was a population-based, retrospective cohort study of delivery hospitalizations within the U.S. International Classification of Disease Tenth Revision (ICD-10) diagnosis and procedure codes were used to identify hospital deliveries, maternal and obstetric co-morbidities, gestational age at delivery, and primary and secondary outcomes. Multivariable logistic regression analysis was used to assess SMM, potentially preventable SMM (pSMM), and maternal mortality risk by admission quarter (Q1: January-March; Q2: April-June; Q3: July-September; Q4: October-December). Secondary outcomes included analysis of individual SMM indicators, SMM by organ system category, and obstetric outcomes.

During the study period, 15,690,250 patients delivered at teaching hospitals. When compared to July-Sept, there were no statistically significant differences in SMM noted across the academic year (Jan-Mar aRR 1.01 [0.97-1.04], Apr-June aRR 1.03 [0.99-1.07], Oct-Dec aRR 1.00 [0.97-1.04]). Additionally, there were no significant differences of pSMM (Jan-Mar aRR 1.01 [0.97-1.05], Apr-June aRR 1.04 [0.99-1.08], Oct-Dec aRR 1.00 [0.96-1.04]) nor maternal death (Jan-Mar aRR 0.97 [0.63-1.49], Apr-June aRR 0.89 [0.57-1.37], Oct-Dec aRR 0.86 [0.56-1.31]) across the academic year when compared to July-Sept. There were no differences noted in rates of eclampsia, sepsis, acute respiratory distress syndrome, or cardiac arrest across the academic year.

There is no difference in SMM, pSMM, or mortality risk during delivery hospitalization across admission quarters at urban teaching hospitals.