title: First trimester antepartum obstetrical ultrasound examination.
authors.forename: D
authors.initials: D
authors.lastname: Gibbens
authors.lastname: Harvey
authors.lastname: Hansen
authors.lastname: Milius
mesh_terms: D005260:Female; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D016216:Ultrasonography, Prenatal / Q000379:methods