Abstract 1999: Gestational Age Below 40 Weeks is Associated With Increased Death Rates in Infants With Congenital Heart Disease
Background: Outcomes for infants with congenital heart disease (CHD) may be impacted by the national trend toward lower gestational age (GA) at delivery. Few population based data assess the significance of GA in late preterm (GA 34 to 36 wks) and term (≥37 wks) infants with CHD. We aim to
describe CHD death rates in infants born between 34 and 40 wks,
estimate the relationship between GA and CHD infant death rates and
compare CHD death rates across 1 and 2 week intervals in GA.
Methods: We analyzed 14.9 million live births using National Health Statistics linked birth-death files from years 2000 –2003. CHD deaths in the first year of life were identified by grouped infant mortality codes. Subgroups were defined by GA. Death rate was calculated using CHD deaths and all live births. A regression based analysis of variance model assessed the relationship between GA and log transformed CHD death rate, adjusting for birth year. Post-hoc comparisons were conducted using Tukey HSD technique.
Results: 4736 CHD deaths occurred in infants born 34 to 40 wks GA (75% of all infant CHD deaths). Death rate decreased with each successive week of GA (R2 = 0.97). Pairwise comparisons for 1 week GA intervals varied in significance (p = 0.02 to 0.23) All 2 week GA intervals were highly significant (p <.0002) after comparing death rates (per 100,000 live births) of 125, 72, 40, and 24 across GA of 34, 36, 38 and 40 wks, respectively.
Conclusions: GA and CHD infant death rate maintain a significant negative linear relationship up to 40 wks. These data challenge our understanding of how the final wks of pregnancy impact CHD outcomes. Such findings could change perinatal management strategies and postnatal risk assessment.