BackgroundInfants with critical congenital heart disease (CCHD) are more likely to be small for gestational age (GA). It is unclear how this affects mortality. The authors investigated the effect of birth weight Z score on 1âyear mortality separately in preterm (GA <37Â weeks), earlyâterm (GA 37â38Â weeks), and fullâterm (GA 39â42Â weeks) infants with CCHD.Methods and ResultsLiveâborn infants with CCHD and GA 22 to 42Â weeks born in California 2007â2012 were included in the analysis. The primary predictor was Z score for birth weight and the primary outcome was 1âyear mortality. Multivariable logistic regression was used. Results are presented as adjusted odds ratios and 95% confidence intervals (CIs). The authors identified 6903 infants with CCHD. For preterm and fullâterm infants, only a Z score for birth weight <â2 was associated with increased mortality compared with the reference group (Z score 0â0.5, adjusted odds ratio, 2.15 [95% CI, 1.1â4.21] and adjusted odds ratio, 3.93 [95% CI, 2.32â6.68], respectively). In contrast, in earlyâterm infants, the adjusted odds ratios for Z scores <â2, â2 to â1, and â1 to â0.5 were 3.42 (95% CI, 1.93â6.04), 1.78 (95% CI, 1.12â2.83), and 2.03 (95% CI, 1.27â3.23), respectively, versus the reference group.Conclusions
GA seems to modify the effect of birth weight Z score on mortality in infants with CCHD. In preterm and fullâterm infants, only the most severe smallâforâGA infants (Z score <â2) were at increased risk for mortality, while, in earlyâterm infants, the risk extended to mild to moderate smallâforâGA infants (Z score <â0.5). This information helps to identify highârisk infants and is useful for surgical planning.