Race, gestational age in neonatal mortality associated with congenital heart defects

**CDC. MMWR. 2010;59:1208-1211.**

The likelihood of neonatal mortality may increase or decrease depending on a combination of maternal race and gestational age among infants born with congenital heart defects, according to recent study data.

Reported all-cause neonatal mortality rates appear higher among term infants born to black mothers compared with term infants born to white mothers. Yet, race seems to have a converse association with all-cause neonatal mortality rates for preterm infants, according to CDC researchers.

To evaluate neonatal mortality associated with congenital heart defects by maternal race and gestational age, the researchers examined linked birth and infant death data from 2003 to 2006 in the United States. Only the records of infants aged younger than 28 days with death certificates citing a congenital heart defect as the underlying cause of death were included in the analysis.

The researchers also restricted racial data to infants born to white or black mothers only. They also excluded infants with missing or implausible gestational ages listed in their medical records. Data were then weighted according to the percentage of records linked by state and age at death.

Among live births that occurred during the study period, 11,383,665 met inclusion criteria. Of 54,008 neonatal deaths, 4.2% of infants had a congenital heart defect listed as the underlying cause — 5.4% of whom were born to white mothers and 2.3% of whom were born to black mothers.

Congenital heart defects accounted for 24.5% of all neonatal deaths, which translated to a mortality rate of two per 10,000 live births, according to the researchers. Hypoplastic left heart syndrome was identified as the congenital heart defect in most deaths, whereas 38% were unspecified.

Data also indicated that significantly fewer deaths related to transposition of the great arteries occurred in infants born to black mothers compared with those born to white mothers, although neonatal deaths resulting from pulmonary atresia were more common in infants born to black mothers compared with those born to white mothers.

Gestational age also appeared to influence neonatal mortality rates attributable to congenital heart defects, according to the researchers. For preterm infants, defined as those born at less than 37 weeks’ gestational age, the rate of deaths related to congenital heart defects was 4.5 per 10,000 live births among infants born to black mothers compared with the 6.8 per 10,000 for those born to white mothers (RR=0.7; P<.001) .

Neonatal mortality rates associated with congenital heart defects for infants born between 37 and 44 weeks were 1.5 per 10,000 for those born to black mothers and 1.3 per 10,000 for those born to white mothers (RR=1.2; P=.03).

“The findings in this report indicate that although the overall neonatal mortality rate from congenital heart defects does not differ significantly between infants born to white and black mothers, differences can be observed by gestational age group,” the researchers wrote.

They also said, however, that the reasons for these differences are unclear and that further research is required into assessment of differences in prenatal diagnosis, prevalence of congenital heart defects at birth and reporting of causes of death.

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