Maternal serum markers for Down syndrome screening in second-trimester and its relations with adverse pregnant outcomes

Abstract

Objective To investigate the relationship between abnormalities of maternal serum markers in Down syndrome screening in second trimester and adverse pregnancy outcome.Methods Totally,1935 pregnant women were screened for Down syndrome with maternal serum tri marker with time-resolved fluorescence assay,including alpha fetoprotein (AFP),free β-human chorionic gonadotropin (β-hCG) and unconjugated estriol (uE3),between 15 and 20+6 gestational weeks at Peking Union Hospital from January 1,2009 to January 31,2011,and were followed up till delivery.The relationship between incidence of adverse pregnancy outcomes and women with normal or abnormal levels of serum markers in Down syndrome screening was investigated.T-test or Chi-square test were applied for statistical comparison.Results (1) Among the 1935 pregnant women,normal levels of serum markers were found in 1255(normal group) and 680 were abnormal(abnormal group),in which 577 with only one abnormal serum marker,89 with two and 14 with three abnormal serum markers.According to the serum marker level,the 577 women with one abnormal serum marker were further divided into five groups,including high AFP group (n=17),low AFP group (n=114),high β-hCG group (n=242),low β-hCG group (n=139) and low uE3 group (n=65).The birth weight of infants in lower AFP group and the gestational age at delivery in low β-hCG group were greater than those in normal group [(61.3±9.1) kg vs (59.5±8.3) kg,(272.6±11.8) d vs (274.4±10.1) d,t=2.21 and 1.99,both P＜0.01].(2) The incidence of adverse pregnancy outcome in normal group was 42.8％(537/1255),while comparing with the abnormal group(43.7％,297/680),no statistical significance was shown (RR =1.02,P =0.71).While comparing with the normal group,the incidences of placenta previa [25.5％ (32/1255) vs 2/17,RR=4.61,P＜0.05] and abnormal placental morphology were higher in high AFP group [4.1％ (51/1255) vs 5/17,RR=7.24,P＜ 0.05],the incidence of gestational diabetes mellitus (GDM) was higher in low AFP group [8.1％ (101/1255) vs 14.4％(16/114),RR=1.74,P＜0.05],the incidence of placenta and membrane retention was higher in high β-hCG group [3.5％ (44/1255) vs 6.2％(15/242),RR=1.77,P＜0.05],the incidence of pre-eclampsia was higher in low β-hCG group [1.7％ (21/1255) vs 6.5％ (9/ 139),RR=3.87,P＜0.05].(3) There were 89 women with two abnormal serum markers.Comparing with the normal group,the incidences of small for gestional age (SGA) infants,oligohydramnios,abruptio placenta were higher in women with low AFP but high β-hCG [SGA infants:6.9％(2/29) vs 1.8％(22/1255),RR=3.94; oligohydramnios:20.7％(6/29) vs 6.4％(80/ 1255),RR=3.24; both P＜0.05],the incidences of oligohydramnios was higher in women with both low AFP and low uE3[3/14 vs 6.4％(80/1255),RR=3.36,P＜0.05],the incidence of premature birth and GDM were higher in women with both low β-hCG and low uE3 [premature birth:2/6 vs 4.3％(54/1255),RR=7.75; GDM:3/6 vs 8.0％ (101/1255),RR=6.21; both P＜0.05].(4) There were 14 women with three abnormal serum markers.The relationship between adverse outcome and abnormal serum markers did not show any statistical significance.Conclusions The abnormality of serum markers of Down syndrome screening is closely related to adverse pregnancy outcomes,and women with abnormal serum markers should be carefully monitored during pregnancy. Key words: Pregnancy trimester, second; Down syndrome; Biological markers; alpha-Fetoproteins; Chorionic gonadotropin, beta sununit, human; Estriol; Pregnancy outcome