*Fetal Development/ph [Physiology] *Twins Adolescent Adult Cohort Studies Continental Population Groups/eh [Ethnology] Female Gestational Age Humans IN PROCESS -- NOT YET INDEXED Maternal Age Pregnancy Quality Assurance, Health Care/st [Standards] Ultrasonography, Prenatal Young Adult
MedStar Washington Hospital Center
Obstetrics and Gynecology/Maternal-Fetal Medicine
Journal Article Multicenter Study Research Support, American Recovery and Reinvestment Act Research Support, N.I.H., Intramural Twin Study