2ND TRIMESTER AMNIOTIC-FLUID ESTRIOL, DEHYDROEPIANDROSTERONE SULFATE, AND HUMAN CHORIONIC-GONADOTROPIN LEVELS IN DOWNS-SYNDROME

Objective - To investigate the reason for low maternal serum unconjugated oestriol (uE3) and raised human chorionic gonadotrophin (hCG) levels in Down's syndrome pregnancies. Design - Measurement of uE3, total oestriol (tE3), dehydroepiandrosterone sulphate (DHEAS), a precursor of oestriol, and hCG in 15-20 week amniotic fluid samples from pregnancies with and without Down's syndrome. Setting - The retrieval and use of stored amniotic fluid samples collected from women who had had an amniocentesis for antenatal diagnosis. Subjects - 45 women with a Down's syndrome pregnancy and 224 unaffected controls of the same gestational age. Results - The median level of amniotic fluid in affected pregnancies was low for uE3, tE, and DHEAS but high for hCG: 0.50, 0-46, 0.35 and 1.58 multiples of the normal median, respectively Conclusion - These results suggest that the abnormal maternal serum levels of uE3, and hCG in affected pregnancies are due mainly to abnormal feto-placental synthesis, rather than feto-maternal transfer.