Current issues in perinatal epidemiology.

The main national data sources for perinatal epidemiology are birth and death certificates, yet routinely linked birth and death certificate data are still not available in the U.S. Completeness and quality of the reporting of perinatal events should be considered in examining trends over time and between jurisdictions. The U.S. has experienced a marked decline in its infant mortality rate, but only a very modest decline in the rate of low birth weight. Research must focus more on studies of pre-term labor, rather than low birth weight, which include children who are underground or who are born too early and who, therefore, may represent different etiologies. Sensitive hormonal tests may provide more precise estimates of the rate of very early fetal loss. Management of labor and delivery and of the high-risk newborn have undergone marked changes during the last 15 years, and yet clinical trials have not played a major role in the evaluation of these changes. The difference in reproductive outcomes between whites and blacks, especially in the rate of low birth weight, have persisted and are not understood. Data bases are becoming available for intergenerational studies to determine whether nature or nurture accounts for this difference.