title: Frequent occurrence of underreporting multiple gestations based on vaginal and abdominal ultrasonograms performed prior to 6 weeks' gestational age.
authors.forename: J D
authors.initials: JD
authors.lastname: Yeast
mesh_terms: D002823:Chorion / Q000000981:diagnostic imaging; D005260:Female; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011272:Pregnancy, Multiple; D014427:Twins; D016216:Ultrasonography, Prenatal