Socioeconomic and state-level differences in prenatal diagnosis and live birth prevalence of Down's syndrome in the United States.
BACKGROUND: Previous studies have shown socioeconomic disparities in the use of prenatal diagnosis in several countries, including France and the United States. Few studies however, have examined the impact of socioeconomic differences in prenatal testing on disparities in the live birth prevalence of congenital anomalies. In this article, we first review and further discuss some of the results of our previously published work that assesses: i) socioeconomic differences in the use of amniocentesis in the United States using data from national birth cohorts; and ii) impact of socioeconomic differences in prenatal diagnosis on the live birth prevalence of Down's syndrome (trisomy 21). We then present the results of a study that explores the potential effects of public policies regarding abortion on state-level differences in the live birth prevalence of Down's syndrome. MATERIALS AND METHODS: We used birth data from the National Center for Health Statistics for the years 1989 to 1991 as well as data from the National Abortion and Reproductive Rights Action League (NARAL) state-by-state review of abortion rights. The main individual-level socioeconomic variables in the analyses were maternal ethnicity and education; the analyses of the interaction effects between maternal age and ethnicity are presented here. Interaction effects were assessed using logistic regression models with likelihood ratio tests. We used hierarchical logistic regression models for analyses of state-level effects while controlling for individual-level socioeconomic factors. RESULTS: We found substantial age-specific socioeconomic differences in the use of amniocentesis and in the rates of age-related increase in the live birth prevalence of Down's syndrome. In particular, African Americans and Mexican Americans were found to have lower odds of amniocentesis use and higher odds of Down's syndrome at birth. In addition, after controlling for maternal age, socioeconomic factors and prenatal care, we found that states which allowed public financing of abortion services for all or most circumstances had lower odds of Down's syndrome at birth. CONCLUSION: Unless socioeconomic differences in prenatal testing are addressed, the increasing use of prenatal testing might result in widening socioeconomic disparities in the live birth prevalence of Down's syndrome and other major congenital anomalies in future years.