title: Screening for Down syndrome at 14 weeks of pregnancy.
abstract: To investigate whether statistical parameters used in Down syndrome screening between 15 and 22 weeks of pregnancy can be used at 14 weeks, we assayed alpha-fetoprotein (AFP), unconjugated oestriol (uE3), total human chorionic gonadotrophin (hCG), free alpha-hCG, free beta-hCG, and inhibin-A in 16 pregnancies with Down syndrome in the 14th week of pregnancy and expressed values in multiples of the normal median. The median and standard deviation values for these 16 pregnancies were not materially different from those published for 15-22 weeks. It is reasonable, therefore, to offer Down syndrome screening using these markers starting at 14 completed weeks of pregnancy instead of 15 weeks. It needs to be recognized, however, that serum AFP measurement for neural tube defect screening is less effective at this time than between 16 and 18 weeks of pregnancy.
authors.affiliation: Department of Environmental and Preventive Medicine, Wolfson Institute of Preventive Medicine, St Bartholomew's and the Royal London School of Medicine and Dentistry, UK.
authors.forename: N J
authors.initials: NJ
authors.lastname: Wald
authors.forename: H C
authors.initials: HC
authors.lastname: Watt
authors.forename: J E
authors.initials: JE
authors.lastname: Haddow
authors.forename: G J
authors.initials: GJ
authors.lastname: Knight
mesh_terms: D006063:Chorionic Gonadotropin / Q000097:blood* / Q000145:classification / Q000378:metabolism; D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis* / Q000196:embryology; D004964:Estriol / Q000097:blood* / Q000378:metabolism; D005260:Female; D005315:Fetal Diseases / Q000097:blood / Q000175:diagnosis* / Q000196:embryology; D005865:Gestational Age; D006801:Humans; D007265:Inhibins; D008403:Mass Screening / Q000379:methods; D010455:Peptides / Q000097:blood* / Q000378:metabolism; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011296:Prenatal Diagnosis / Q000379:methods*; D000509:alpha-Fetoproteins / Q000032:analysis* / Q000378:metabolism
chemical_list: D006063:Chorionic Gonadotropin; D010455:Peptides; D000509:alpha-Fetoproteins; C094377:inhibin-alpha subunit; D007265:Inhibins; D004964:Estriol