Maternal serum hCG and SP1 in pregnancies with fetal aneuploidy.

In a retrospective study, maternal serum levels of chorionic gonadotropin (hCG) and pregnancy specific beta 1-glycoprotein (SP1) from 63 pregnancies with aneuploid fetuses were compared to the levels observed in pregnancies with a chromosomally normal fetus. Thirty-eight percent of the abnormal pregnancies had elevated levels (greater than 2.0 multiples of the normal median [MoM]) of hCG and 14% had depressed levels (less than 0.25 MoM). With a false-positive rate of 5%, 44% of the 42 fetuses with trisomy 21 would have been detected by elevated hCG levels. With the same false-positive rate, only 21% had elevated SP1 levels. hCG was significantly depressed in 12 pregnancies affected by fetal trisomy 18.