title: The estimation of gestational age of pregnancy for use in screening for Down syndrome using ultrasound measurements and embryo transfer date.
authors: Wayne J
authors: WJ
authors: Huttly
authors: Nicholas J
authors: NJ
authors: Wald
mesh_terms: D018568:Crown-Rump Length; D004314:Down Syndrome / Q000000981:diagnostic imaging*; D004624:Embryo Transfer; D005188:False Negative Reactions; D005260:Female; D005307:Fertilization in Vitro; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D013997:Time Factors; D016216:Ultrasonography, Prenatal