A prenatal trisomy 21 screening program using alpha-fetoprotein, human chorionic gonadotropin, and free estriol assays on maternal dried blood.

Objective: The feasibility of large-scale Down syndrome maternal screening with dried blood samples and nonradioactive methods was examined.

Study Design: A prospective observation study was performed on a nonselected population of 11,241 pregnant women sampled between January 1991 and September 1992, between 14 and 24 weeks' gestation (ultrasonographic scanning available for 91.6%), through a multicenter collaborative network.