title: Dating pregnancy. Gathering and using a reliable data base.
authors.forename: C
authors.initials: C
authors.lastname: Nichols
mesh_terms: D005260:Female; D005865:Gestational Age; D006801:Humans; D008598:Menstruation; D011247:Pregnancy; D011295:Prenatal Care / Q000379:methods*; D014463:Ultrasonography; D014599:Uterus / Q000033:anatomy & histology