title: Early pregnancy: normal and abnormal.
authors.affiliation: Reproductive Science Center of Western Massachusetts, East Longmeadow 01028, USA.
authors.forename: R S
authors.initials: RS
authors.lastname: Howe
mesh_terms: D018568:Crown-Rump Length; D005321:Extraembryonic Membranes / Q000000981:diagnostic imaging*; D005260:Female; D006340:Heart Rate, Fetal / Q000502:physiology; D006801:Humans; D010388:Pelvis / Q000000981:diagnostic imaging*; D017410:Practice Guidelines as Topic; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011272:Pregnancy, Multiple; D016216:Ultrasonography, Prenatal