title: Estimation of risk in second trimester serum screening for Down syndrome among women who have already had first trimester screening.
authors.forename: Allan
authors.initials: A
authors.lastname: Hackshaw
authors.forename: Nicholas
authors.initials: N
authors.lastname: Wald
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis*; D015987:Effect Modifier, Epidemiologic; D005260:Female; D006801:Humans; D008403:Mass Screening / Q000379:methods; D008423:Maternal Age; D009333:Neck / Q000000981:diagnostic imaging / Q000196:embryology; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D018566:Pregnancy, High-Risk; D018570:Risk Assessment; D012307:Risk Factors; D016216:Ultrasonography, Prenatal
chemical_list: D015415:Biomarkers