Urinary beta-core hCG: screening for aneuploidies in early pregnancy (11-14 weeks' gestation).

Initial studies at 17-22 weeks' gestation evaluating urinary beta-core human chorionic gonadotrophin (hCG) as a marker for Down's syndrome had suggested that it may have more potential than its serum counterpart. This study measured maternal urinary beta-core-hCG and creatinine at 11-14 weeks' gestation in a series of 26 aneuploidies (nine trisomy 21, five trisomy 18, four 45,X0, and eight others). The normal range for beta-core-hCG and beta-core-hCG/ creatinine was derived from 198 normal singleton pregnancies. Trisomy 18 cases (n = 5) had low maternal urinary beta-core-hCG creatinine levels (median 0.35 MOM, range 0.08-0.82 MOM). Whereas the other aneuploidies had no particular pattern; in particular, the trisomy 21 cases (n = 9) (median 1.16 MOM, range 0.3-4.74 MOM) did not differ significantly from 1 MOM. The findings imply that maternal urinary beta-core-hCG is not as discriminating for Down's syndrome between 11 and 14 weeks as later on in pregnancy.