Prenatal screening for trisomy 21: a comparative performance and cost analysis of different screening strategies.

Background: Prenatal screening for chromosome aneuploidies have constantly been evolving, especially with the introduction of cell-free fetal DNA (cfDNA) screening in the most recent years. This study compares the performance, costs and timing of test results of three cfDNA screening implementation strategies: contingent, reflex and primary.

Methods: We modelled enhanced first trimester screening (eFTS) as the first-tier test in contingent or reflex strategies.