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

The aim of this study was to investigate the second trimester concentrations of maternal urine human chorionic gonadotrophin beta-core fragment (HCG beta cf) in Asian pregnancies with fetal chromosomal abnormalities. HCG beta cf concentrations were analysed from 34 urine samples in chromosomally abnormal pregnancies, including 28 cases of Down's syndrome, one case of trisomy 18, and five cases of other chromosomal abnormalities (one mosaic deletion and four translocations), and in a cohort of 268 normal pregnancies receiving second trimester amniocentesis. Results were normalized to urine creatinine (Cr) concentration and converted to the multiple of the median (MOM) concentration for the appropriate gestation. The median HCG beta cf MOM concentrations of Down's syndrome pregnancies (12.89) was significantly higher than that of normal pregnancies (1.06) (P < 0.00001). Wide variations of HCG beta cf concentrations were observed in other chromosomally abnormal pregnancies. There were 18 of 28 (64%) Down's syndrome cases but one of five (20%) other chromosomally abnormal cases with HCG beta cf concentrations above the 95th centile of the control values (8.22 MOM cut-off). These findings suggest that HCG beta cf could be a potential marker in urine screening for fetal Down's syndrome in Asians.