Neonatal Mortality After Interhospital Transfer of Pregnant Women for Imminent Very Preterm Birth in Illinois

Abstract

Importance: Reducing neonatal mortality is a national health care priority. Understanding the association between neonatal mortality and antenatal transfer of pregnant women to a level III perinatal hospital for delivery of infants who are very preterm (VPT) may help identify opportunities for improvement.

Objective: To assess whether antenatal transfer to a level III hospital is associated with neonatal mortality in infants who are VPT.

Design, setting, and participants: This population-based cross-sectional study included infants who were born VPT to Illinois residents in Illinois perinatal-network hospitals between January 1, 2015, and December 31, 2016, and followed up for 28 days after birth. Data analysis was conducted from June 2017 to September 2018.

Exposures: Delivery of an infant who was VPT at a (1) level III hospital after maternal presentation at that hospital (reference group), (2) a level III hospital after antenatal (in utero) transfer from another hospital, or (3) a non-level III hospital.

Main outcomes and measures: Neonatal mortality.

Results: The study included 4817 infants who were VPT (gestational age, 22-31 completed weeks) and were born to Illinois residents in 2015 and 2016. Of those, 3302 infants (68.5%) were born at a level III hospital after maternal presentation at that hospital, 677 (14.1%) were born at a level III hospital after antenatal transfer, and 838 (17.4%) were born at a non-level III hospital. Neonatal mortality for all infants who were VPT included in this study was 573 of 4817 infants (11.9%). The neonatal mortality was 10.7% for the reference group (362 of 3302 infants), 9.8% for the antenatal transfer group (66 of 677 infants), and 17.3% for the non-level III birth group (145 of 838 infants). When adjusted for significant social and medical characteristics, infants born VPT at a level III hospital after antenatal transfer from another facility had a similar risk of neonatal mortality as infants born at a level III hospital (odds ratio, 0.79 [95% CI, 0.56-1.13]) after maternal presentation at the same hospital. Infants born at a non-level III hospital had an increased risk of neonatal mortality compared with infants born at a level III hospital after maternal presentation to the same hospital (odds ratio, 1.52 [95% CI, 1.14-2.02]).

Conclusions and relevance: The risk of neonatal mortality was similar for infants who were VPT, whether women initially presented at a level III hospital or were transferred to a level III hospital before delivery. This suggests that the increased risk of mortality associated with delivery at a non-level III hospital may be mitigated by optimizing opportunities for early maternal transfer to a level III hospital.

Figure.. Study Groups of Very Preterm (VPT) Births in Illinois in 2015 and 2016

The reference group is the 3302 infants born to mothers who presented and delivered at level III hospitals. The antenatal transfer group includes the 677 infants born to women who were transferred to a level III hospital. The non–level III hospital group includes the 838 infants born at non–level III hospitals. The reference, antenatal transfer, and non-level III birth groups represent the study groups. Together, the reference and antenatal transfer group represent inborn infants who were VPT.