FIRST-TRIMESTER URINE FREE BETA-HCG, BETA-CORE, AND TOTAL ESTRIOL IN PREGNANCIES AFFECTED BY DOWNS-SYNDROME - IMPLICATIONS FOR FIRST-TRIMESTER SCREENING WITH NUCHAL TRANSLUCENCY AND SERUM-FREE BETA-HCG

We have examined maternal urine concentrations of beta core, free beta human chorionic gonadotrophin (hCG), and total oestriol in 373 contro l pregnancies and 43 pregnancies affected by aneuploidy (including 22 cases of Down's syndrome) in an attempt to see if any of the analytes have a value in Down's syndrome screening between the tenth and 14th w eek of pregnancy. We have compared the performance of these analytes a gainst nuchal translucency measurement combined with maternal serum fr ee beta hCG at the same period of pregnancy. Our results show that lev els of urine free beta hCG and beta core are increased in Down's syndr ome with average multiple of the median levels of 1.81 and 2.91, respe ctively. Urine total oestriol was reduced (0.83) whilst maternal serum free beta hCG was increased (1.72). In trisomy Is the levels of all a nalytes were reduced, although serum free beta hCG was the most discri minating. The spread of results in the control and the Down's group fo r urine beta core was more than three times than that for serum free b eta hCG and with urine free beta hCG it was two times wider. In combin ation with maternal age, urine total oestriol had a 32 per cent detect ion rate at a fixed 5 per cent false-positive rate; urine beta core 34 per cent, urine free beta hCG 36 per cent, maternal serum free beta h CG 44 per cent, and nuchal translucency 82 per cent. In combination wi th nuchal translucency, urine total oestriol added an extra 1 per cent detection, urine beta core an extra 2 per cent, urine free beta hCG a n extra 3 per cent, and serum free beta hCG an extra 5 per cent. It is unlikely that any of the urine markers will be of value in first-trim ester screening. Optimal first-trimester screening programmes will rel y for the foreseeable future on nuchal translucency, serum free beta h CG, and possibly pregnancy-associated plasma protein A. (C) 1997 by Jo hn Wiley & Sons, Ltd.