title: First trimester biochemical screening for trisomy 21.
authors.forename: T M
authors.initials: TM
authors.lastname: Reynolds
mesh_terms: D000649:Amniocentesis; D015193:Chorionic Villi Sampling; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D005820:Genetic Testing; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First