Investigation of a temporal cluster of left sided congenital heart disease.

During October and November 1977, eight newborns with critical congenital heart disease, six of these with left sided lesions, were admitted to a New Jersey newborn unit serving two predominantly rural counties with 9700 annual live births. The six left heart lesions (three cases of hypoplastic left heart, two of interrupted aortic arch, and one of aortic coarctation) represented 30% of all neonatal left sided lesions seen at the unit in the three year period 1976-8. The scan statistic for temporal clustering was significant (p less than 0.05). A case-control study was performed in which an average of four controls were matched to each case. A questionnaire was administered to the mothers of cases and controls concerning occupation, periconceptional and prenatal nutrition, radiation and chemical exposure, use of alcohol and tobacco, medications, immunisations, infections, and other exposures. No statistically significant differences between cases and controls were found on any of these items. Although no aetiology for this cluster of congenital heart anomalies could be found, it is of interest that three temporal clusters of fetuses or newborns with chromosomal trisomies have been reported in the medical literature whose conceptions were roughly contemporaneous with those of the infants in our series. These occurred in Rhode Island/Massachusetts, Maryland, and New York City. A speculative possibility is that these four point epidemics represented exposure to a common teratogenic agent, perhaps influenza B, in the winter of 1976/77 in the northeastern United States.