title: The effect of weight correction on risk calculations for Down's syndrome screening.
abstract: Recent advances in prenatal screening have led to the possibility that the risk of Down's syndrome associated pregnancy may be assessed by blood tests for maternal serum alphafetoprotein, human chorionic gonadotrophin (and possibly unconjugated oestriol) taken at 15-18 weeks of gestation. In neural tube defect screening correction of maternal serum alphafetoprotein for maternal weight has been recommended, although the precise method for weight correction is still under debate. We report an assessment of weight correction for maternal serum alphafetoprotein and human chorionic gonadotrophin based on 1408 singleton pregnancies and for unconjugated oestriol based on 197 singleton pregnancies. We demonstrate that weight correction of maternal serum alphafetoprotein and human chorionic gonadotrophin is statistically valid but that correction of unconjugated oestriol is not.
authors.affiliation: Medical Biochemistry Department, University Hospital of Wales, Heath Park, Cardiff, UK.
authors.forename: T M
authors.initials: TM
authors.lastname: Reynolds
authors.forename: M D
authors.initials: MD
authors.lastname: Penney
authors.forename: H
authors.initials: H
authors.lastname: Hughes
authors.forename: R
authors.initials: R
authors.lastname: John
mesh_terms: D001835:Body Weight; D006063:Chorionic Gonadotropin / Q000097:blood; D004314:Down Syndrome / Q000175:diagnosis*; D004964:Estriol / Q000097:blood; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis*; D005865:Gestational Age; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy / Q000097:blood*; D011296:Prenatal Diagnosis; D012307:Risk Factors; D000509:alpha-Fetoproteins / Q000378:metabolism
chemical_list: D006063:Chorionic Gonadotropin; D000509:alpha-Fetoproteins; D004964:Estriol