AUSTIN, TEX. – A first look at the timing of neonatal deaths showed an association with weekend deliveries in one Texas county. However, birth weight and ethnicity attenuated the association, according to a recent study. Higher hospital volumes were associated with lower risk of neonatal deaths.
The retrospective, population-based cohort study, presented during the annual clinical and scientific meeting of the American College of Obstetricians and Gynecologists, used data from birth certificates and infant death certificates in the state of Texas. The investigators, said Elizabeth Restrepo, PhD, chose to examine data from Tarrant County, Tex., which has historically had persistently high infant mortality rates; in 2013, she said, the infant mortality rate in that county was 7.11/1,000 births – the highest in the state for that year.
The first question Dr. Restrepo and her colleagues at Texas Women’s University, Denton, wanted to answer was whether there was an association between the risk of neonatal mortality and the day of the week of the birth. For this and the study’s other research questions, she and her colleagues looked at 2012 data, matching 32,140 birth certificate records with 92 infant death certificates.
The investigators found an independent association between the risk of neonatal death and whether the birth happened on a weekday (Monday at 7:00 a.m. through Friday at 6:59 p.m.), or on a weekend (Friday at 7:00 p.m. through Monday at 6:59 a.m.). However, once birth weight and ethnicity were controlled in the statistical analysis, the association was not statistically significant despite an odds ratio of 1.44 (95% confidence interval, 0.911-2.27; P = .119).
“Births in the 12 hospitals studied appear to have been organized to take place more frequently on the working weekday rather than weekend days,” wrote Dr. Restrepo and her colleagues in the poster accompanying the presentation. Although the study wasn’t designed to answer this particular question, Dr. Restrepo said in discussion during the poster session that planned deliveries, such as inductions and cesarean deliveries, are likely to happen during the week, while the case mix is wider on weekends. Patient characteristics, as well as staffing patterns, may come into play.
The researchers also asked whether birth volume at a given institution increases the odds of neonatal death on weekends. Here, they found a significant inverse relationship between hospital birth volume and neonatal deaths (r = –0.021; P less than .001). With each additional increase of 1% in the weekday birth rate, the odds of neonatal death dropped by approximately 7.4%.
Examining the Tarrant County data further, Dr. Restrepo and her colleagues found that the hospitals with higher birth volumes had a more even distribution of births across the days of the week, with resulting lower concentrations of births during the week (r = –.394; P less than .001).