Mortality among infants with birth defects: Joint effects of size at birth, gestational age, and maternal race/ethnicity.

Background: We examined the separate and joint effects of gestational age, size at birth and maternal race/ethnicity on early childhood survival among 48,391 singleton infants with major birth defects.

Methods: Texas Birth Defects Registry data were linked to death records and the National Death Index to ascertain deaths. Gestational age categories were preterm or term birth; size at birth included small for gestational age (SGA), appropriate for gestational age (AGA), and large for gestational age (LGA). Kaplan-Meier survival estimates were calculated, and Cox-proportional hazards models were used to calculate hazard ratios (HR) and 95% confidence intervals (CI) to determine risk of death after adjusting for covariates.

Results: Overall, relative to non-Hispanic (NH) -whites, NH-blacks, and Hispanics had a 51 and 10% greater risk of death during early childhood, respectively. Compared to NH-whites born term and AGA (survival = 97%), Hispanic children born SGA and preterm had the greatest risk of death (HR(a) = 6.1; 95% CI, 5.2, 7.2) and the lowest early childhood survival (76%), followed by SGA preterm NH-blacks (HR(a) = 4.8; 95% CI, 3.6, 6.5; survival = 81%) and SGA preterm NH-whites (HR(a) = 4.5; 95% CI, 3.7, 5.6; survival = 83%). Children born LGA at term had no increased risk of mortality regardless of maternal race/ethnicity.

Conclusions: The joint effect of gestational age and size at birth had greatest impact on childhood mortality. Additional population based studies are needed to better understand causes of racial/ethnic disparities in mortality among children with birth defects.