Racial Differences by Gestational Age in Neonatal Deaths Attributable to Congenital Heart Defects --- United States, 2003--2006

Racial Differences by Gestational Age in Neonatal Deaths Attributable to Congenital Heart Defects --- United States, 2003--2006
Weekly
September 24, 2010 / 59(37);1208-1211


Congenital heart defects are diagnosed in approximately 1% of births in the United States (1) and account for the largest proportion of infant mortality attributable to birth defects (2). Congenital heart defects are multifactorial in origin and have several recognized genetic causes (e.g., DiGeorge and Williams-Beuren syndromes) (3) and noninherited risk factors (e.g., maternal pregestational diabetes and rubella infection) (4). Approximately 70% of infant deaths attributable to congenital heart defects occur neonatally (age <28 days) (5). U.S. studies have shown that all-cause neonatal mortality rates are higher among term infants of black mothers compared with white mothers, but lower among preterm infants of black mothers compared with white mothers (6,7). To assess neonatal mortality attributable to congenital heart defects by maternal race and gestational age, CDC analyzed linked U.S. birth and infant death data for 2003--2006. This report summarizes the results of that analysis, which found that 4.2% of all neonatal deaths and 24.5% of neonatal deaths attributable to birth defects had a congenital heart defect noted as the underlying cause. Among preterm births (<37 completed weeks' gestation), neonatal mortality rates attributable to congenital heart defects were lower for blacks (4.5 per 10,000 live births) compared with whites (6.8). However, among term births (≥37 completed weeks' gestation), neonatal mortality rates attributable to congenital heart defects were higher for blacks (1.5 per 10,000 live births) than for whites (1.3). The reasons for these racial differences by gestational age are unclear and will require further examination, including assessment of differences in prenatal diagnosis and prevalence at birth of congenital heart defects, and reporting of causes of death.

This analysis used 2003--2006 linked* birth/infant death data, the most recent available.† Included were records of all neonates (aged <28 days) whose underlying cause of death on the death certificate was classified as a congenital heart defect according to the International Classification of Diseases, 10th Revision, with codes Q20.0--Q26.9 (excluding Q21.1, persistent foramen ovale§ and Q25.0, patent ductus arteriosus, because these are considered normal conditions of prematurity). The analysis was restricted to infants of white and black mothers as reported on the birth certificate; those of Hispanic ethnicity and other racial/ethnic groups were excluded. Linked records with a missing gestational age (0.6% of the total), those with implausible gestational ages based on Alexander's index of birth weight for gestational age norms (0.6%) (6), and those with gestational ages <20 weeks or >44 weeks (1.1%) were excluded.

Because not all infant death records could be linked to the corresponding birth certificate, estimates of neonatal deaths were weighted according to the percentage of records linked by state and age at death. Poisson regression was used to calculate the rate ratio (RR) comparing neonatal mortality attributable to congenital heart defects among infants of black mothers with white mothers by gestational age group. Congenital heart defect neonatal mortality rates by weeks of gestational age also were estimated for infants of black mothers compared with white mothers.

The analysis included 11,383,665 live births in the United States during 2003--2006. Overall, of 54,008 neonatal deaths, 2,256 (4.2%) had a congenital heart defect noted as the underlying cause, including 1,777 (5.4%) of 33,205 infants of white mothers and 479 (2.3%) of 20,803 infants of black mothers. Deaths attributable to congenital heart defects were 24.5% of all neonatal deaths attributable to birth defects. The neonatal mortality rate attributable to congenital heart defects was 2.0 per 10,000 live births (Table 1). Hypoplastic left heart syndrome was the most commonly specified congenital heart defect--related underlying cause of neonatal death for infants of white (480 [27%]) and black (126 [26%]) mothers; 38% of the deaths were listed as "congenital malformation of heart, unspecified" (Table 2). A significantly lower proportion of neonatal deaths with transposition of the great arteries as the underlying cause occurred in infants of black mothers (2%) compared with white mothers (6%), but a significantly higher proportion of neonatal deaths caused by pulmonary atresia occurred in infants of black mothers (3%) compared with white mothers (2%).

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Racial Differences by Gestational Age in Neonatal Deaths Attributable to Congenital Heart Defects --- United States, 2003--2006