title: Which gestational age estimate to use in AFP screening for spina bifida?
authors: Nicholas J
authors: NJ
authors: Wald
mesh_terms: D005260:Female; D005865:Gestational Age; D006801:Humans; D008403:Mass Screening; D011247:Pregnancy; D011296:Prenatal Diagnosis; D016136:Spina Bifida Occulta / Q000175:diagnosis*; D000509:alpha-Fetoproteins / Q000032:analysis*
chemical_list: D000509:alpha-Fetoproteins