Second-trimester maternal urine human chorionic gonadotrophin beta-core fragment concentrations in Asian pregnancies with fetal chromosomal abnormalities

The aim of this study was to investigate the second trimester concentration s of maternal urine human chorionic gonadotrophin beta-core fragment (HCG b eta cf) in Asian pregnancies with fetal chromosomal abnormalities. HCG beta cf concentrations were analysed from 34 urine samples in chromosomally abn ormal pregnancies, including 28 cases of Down's syndrome, one case of triso my 18, and five cases of other chromosomal abnormalities (one mosaic deleti on and four translocations), and in a cohort of 268 normal pregnancies rece iving second trimester amniocentesis. Results were normalized to urine crea tinine (Cr) concentration and converted to the multiple of the median (MOM) concentration for the appropriate gestation. The median HCG beta cf MOM co ncentrations of Down's syndrome pregnancies (12.89) was significantly highe r than that of normal pregnancies (1.06) (P < 0.00001). Wide variations of HCG beta cf concentrations were observed in other chromosomally abnormal pr egnancies. There were 18 of 28 (64%) Down's syndrome cases but one of five (20%) other chromosomally abnormal cases with HCG beta cf concentrations ab ove the 95th centile of the control values (8.22 MOM cut-off). These findin gs suggest that HCG beta cf could be a potential marker in urine screening for fetal Down's syndrome in Asians.