title: Maternal serum free beta-human chorionic gonadotrophin levels in twin pregnancies: implications for screening for Down's syndrome.
abstract: Free beta-human chorionic gonadotrophin values are, on average, 1.90 times greater in twin pregnancies than in singleton pregnancies [95 per cent confidence interval (CI) 1.69-2.13]. This information can be used in screening for Down's syndrome, so that twin pregnancies can be interpreted in addition to singleton pregnancies.
authors.affiliation: Department of Environmental and Preventive Medicine, Wolfson Institute of Preventive Medicine, St Bartholomew's Hospital Medical College, London, U.K.
authors.forename: N J
authors.initials: NJ
authors.lastname: Wald
authors.forename: J W
authors.initials: JW
authors.lastname: Densem
mesh_terms: D006063:Chorionic Gonadotropin / Q000097:blood*; D004200:Diseases in Twins / Q000175:diagnosis*; D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis*; D005260:Female; D005819:Genetic Markers; D005820:Genetic Testing / Q000379:methods*; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy
chemical_list: D006063:Chorionic Gonadotropin; D005819:Genetic Markers