[Evaluation of Down's syndrome screening methods using maternal serum biochemistry in the second trimester pregnancy].

Objective: To provide basis for selecting the suitable method of Down's syndrome biochemical screening in the second trimester pregnancy.

Methods: A total of 30 547 singleton pregnancies between 14 and 20(+ 6) weeks of pregnancy were collected and analyzed for maternal serum alpha-fetoproteins (AFP) and human chorionic gonadotrophin, free beta subunit (beta-HCG) with or without unconjugated estriol (uE3). The screening risks were calculated using the software Lifecycle.