Population Study of the Risk of Fetal Death and Its Relationship to Birthweight, Gestational Age, and Race

ABSTRACT

With more than 20,000 fetal deaths occurring annually in the United States, accurate epidemiological data concerning fetal death offer the potential to develop interventions aimed at saving a considerable number of fetuses. Currently, fetal death rates are determined by dividing the number of deaths by total births. These raw death rates do not focus on cause or preventability, nor do they delineate the risk for a individual pregnancy or any specific gestational age. Using data from 747,033 births in Illinois from 1984 to 1988, we estimated the fetal death risk (FDR) according to fetal weight and gestational age expressed as a function of the number of remaining fetuses. This procedure permits the comparison of FDR across all weights (including fetuses with growth retardation and macrosomia) and gestational ages. In addition, we examined the effect of race on this analysis. Between 28 and 36 weeks' gestational age, white fetuses with mean weights have a constant risk of fetal death at 0.1/1000 remaining fetuses. The risk is two to three times greater for black fetuses. If the fetus has growth retardation or is appropriately grown beyond 37 weeks' gestational age, the FDR increases further, with black fetuses remaining at higher risk. These data attempt to quantify the risk of fetal death. They support the widely held belief that the risk of fetal death increases in the presence of intrauterine growth retardation, but they also demonstrate that the risk of fetal death for all fetuses, including those appropriately grown, increases exponentially after 37 weeks' gestational age. Further research is needed to identify the causes of the observed racial differences in FDR, as well as those factors contributing to increased FDR within each race for appropriately grown, term fetuses.

Keywords

Fetal death risk - birthweight - race