目前许多中心已用孕中期的母血甲胎蛋白(AFP),游离雌三醇(uE_3)和人绒毛膜促性腺激素(hCG)与母亲年龄结合筛选Down综合征,但主要用于单胎诊断,对双胎妊娠诊断尚无经验。本文分析35150例妊娠中410例双胎。双胎的分析值首先用未受累单胎人群均值并结合已报告的双胎妊娠各项水平,用中位数的倍数(MoM)表示。各组参数的 At present, many centers have screened for Down syndrome with maternal serum alpha-fetoprotein (AFP), free estriol (uE_3), and human chorionic gonadotropin (hCG) during the second trimester of pregnancy but are mainly used for single-fetus diagnosis , There is no experience in the diagnosis of twin pregnancy. This article analyzes 35150 cases of pregnancy in 410 cases of twins. Twins were first analyzed in terms of the mean unaffected singleton population combined with the reported levels of twin pregnancies and expressed as a multiple of the median (MoM). The parameters of each group