Objective To investigate the predictive value of abnormal multiples of the median (MoM) of second trimester maternal serum triple screening (STMSTS) markers for adverse pregnancy outcomes.Methods 16 000 singleton pregnancies at 15+0 to 20+6 weeks' gestation who underwent STMSTS between July 2010 and January 2013 in the First Hospital of Jilin University were recruited.Maternal serum AFP,free β-hCG (F-β-hCG) and unconjugated estriol (uE3) levels were measured using time-resolved fluoroimmunoassay,and then convened to MoM.LifeCycle 3.2 software was used to calculate risk,and a risk value greater than 1 in 270 or 1 in 350 was considered as high risk for trisomy 21 syndrome (Down syndrome,DS) and trisomy 18 syndrome (Edwards syndrome,ES),respectively.MoM of AFP more than 2.5was considered high risk for open neural tube defect (ONTD).Amniocentesis and karyotyping,ultrasound screening were advised for high risk women.AFP,F-β-hCG higher than 2.0 MoM or uE3 lower than 0.5MoM was considered as abnormal,respectively.The MoM of STMSTS marker between women with adverse pregnancy outcome and with normal outcome was compared.Results (1) The median MoM of AFP,F-β-hCG and uE3 was 0.91 MoM,0.94 MoM and 1.05 MoM,respectively.Of the 16 000 pregnant women,there was no statistical difference in the median MoM of triple screening marker at different weeks of gestation (P＞0.05).The positive rate of DS,ES and ONTD in women ≤35 years old (n=14 972) was 4.03％ (603/14 972),0.36％(54/14 972) and 0.29％(44/14 972) respectively.And in women＞35 years old(n=1 028),the positive rate was 24.51％ (252/1 028),1.95％ (20/1 028) and 0.78％ (8/1 028),respectively.There was a statistically significant difference of positive rate between the two groups(P＜0.05).(2) 9 cases of DS,1 case of ES and 1 ease of ONTD were found in the high risk group,and 2 cases of DS in the low risk group.The detection rate of DS,ES and ONTD was 9/11,1/1 and 1/1 respectively; and the positive predictive value was 1.05％(9/855),1.35％(1/74) and 1.92％(1/52),respectively.(3)The incidence of adverse outcome (group 1) was 1.49 ％(239/16 000).7 760 pregnant women in this study were healthy during pregnancy,so were their fetuses (group 2).There were significant differences in the age at delivery,body weight and markers' MoM of STMSTS between the two groups(P＜0.01).(4) In group 1,the rate of abnormal MoM of AFP or F-β-hCG was 7.95％(19/239) and 23.85％ (57/239),and the abnormal rate of MoM of uE3 was 4.18％(10/239).The rate of two abnormal MoM of markers was 5.02％(12/239); the rate that all three MoM were abnormal was 0.84％(2/ 239).However,in group 2,the rate of two abnormal MoM of markers was 0.14 ％(11/7 760); and the rate that all three MoM were abnormal was 0.There was a significant difference of abnormal MoM of maternal serum marker between the two groups (P＜0.01).Conclusions There is a relationship between abnormal marker of STMSTS and adverse outcomes.STMSTS show a high value in the detection of DS,ES and ONTD.