437 - Race and Gestational Age-Specific Infant Mortality in the United States

Poster Board #: 437
Publication #: 4905-HP-QA.437

Background: The significant racial disparity in infant mortality rates (IMR) in the United States may be related to differences in gestational age (GA) distribution and possibly GA-specific mortality.


Objective: Test the hypothesis that Black infants have lower GA-specific IMR at the lowest gestations but higher GA-specific IMR at later gestations compared with White infants.


Design/Methods: This study included live-born infants from 22-42 weeks GA with Black or White maternal race and a known birth weight contained within the 2007-2018 CDC WONDER Linked Birth-Infant Death Records database. Deaths due to congenital anomalies were excluded. GA-specific IMR and IMR as a proportion of all live-births were calculated for each GA week. Data were compared by race on both absolute and population-weighted scales using Chi-square to estimate the relative risk (RR) and 95% confidence intervals (CI). Kaplan-Meier survival analyses were performed using available time points (<1 hour, 1-23 hours, 1-6 days, 7-27 days, 28-364 days) to determine differences in timing of infant mortality by race and GA.


Results: There were 42,778,252 infants included of whom 7,465,502 (17.5%) were Black and 35,312,750 (82.5%) were White. The overall IMR rate was 7.6 per 1000 among Black infants and 3.3 per 1000 among White infants. Black infants had lower GA-specific IMR from 22-25 weeks GA compared with White infants (all p<0.05) [Figure 1]. GA-specific IMR did not differ by race at 26 weeks GA. Black infants had higher GA-specific IMR at all GAs from 27-42 weeks compared with White infants (all p<0.05). Population-weighted IMRs were higher among Black infants compared with White infants at each GA [Figure 2]. Timing of death differed by race and GA with lower rates of early mortality but higher post-neonatal mortality among Black infants from 22-27 weeks GA, no difference in early mortality but higher post-neonatal mortality among Black infants from 28-35 weeks GA, and higher early and post-neonatal mortality among Black infants from 36-42 weeks GA compared with White infants.

Conclusion(s): Gestational age-specific infant mortality rates differ by race. While Black infants have lower IMR at the lowest gestations, mortality was higher from 27-42 weeks’ gestation compared with white infants. At a population level, Black infants are at higher risk of death at each GA and point estimates increase with decreasing GA likely secondary to the higher preterm birth rate among Black infants. Timing of infant mortality varies by race and GA suggesting potential targets for intervention.


Figure 1: Gestational age-specific infant mortality by race. Black infants had a lower risk of mortality at 22-25 weeks’ gestation, no difference at 26 weeks’ gestation, and higher infant mortality from 27-42 weeks’ gestation compared with White infants.


Figure 2: Population-weighted infant mortality by race and gestational age. Black infants had higher risk of infant mortality compared with white infants at each gestational age from 22-42 weeks.

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Authors/Institutions: Emily M. Youngblood, The University of Alabama at Birmingham Department of Pediatrics, Birmingham, Alabama, United States; Vivek V. Shukla, University of Alabama at Birmingham, Birmingham, Alabama, United States; Rachel Tindal, The University of Alabama at Birmingham School of Medicine, Birmingham, Alabama, United States; Waldemar Carlo, University of Alabama at Birmingham, Birmingham, Alabama, United States; Colm Travers, University of Alabama at Birmingham, Birmingham, Alabama, United States