Hyperglycosylated-hCG (h-hCG) and Down syndrome screening in the first and second trimesters of pregnancy

OBJECTIVE: To validate Down syndrome screening protocols that include hyperglycosylated-hCG (h-hCG) measurements. METHODS: Measuring h-hCG in 21 641 fresh first- and second-trimester maternal serum samples, but not for clinical interpretation. Nuchal translucency (NT) and pregnancy associated plasma protein-A (PAPP-A) measurements were available in the first trimester; alpha-fetoprotein (AFP), unconjugated estriol (uE3), and human chorionic gonadotropin (hCG) measurements in the second trimester. RESULTS: Of the 23 first- and 26 second-trimester Down syndrome pregnancies identified, 52 and 65% of h-hCG measurements were above the 95th centile, respectively. At a 3% false positive rate, maternal age, NT, PAPP-A and h-hCG detected 78% of cases (95% CI, 56-93%). Other combinations were consistent with previous modeling utilizing stored samples. A literature summary indicates h-hCG is as strong a marker as free-beta between 10 and 13 weeks' gestation. CONCLUSIONS: Down syndrome screening performance of h-hCG using fresh samples meets published expectations based on stored samples. h-hCG could replace free beta measurements, at gestational ages as early as 10 weeks.