The subjects enrolled in both cohorts are seen at the Regional Perinatal Center for management of high-risk pregnancies. As part of intensified obstetrical care, ultrasound evaluation of interval fetal growth with an assessment of estimated fetal weight, average gestational size, and amniotic fluid index is standard around 28 weeks gestation and again at about 35 weeks gestation. Umbilical artery Doppler studies are usually reserved for fetuses with a diagnosis of suspected intrauterine growth restriction. Fetal middle cerebral artery peak flow velocity studies are usually reserved for suspected severe fetal anemia and have been used on an investigational basis for suspected intrauterine growth restriction. We anticipate most subjects will not have a pregnancy complicated by IUGR, therefore performing Doppler studies for umbilical artery S/D ratio and middle cerebral arterial peak velocity will not be standard care. Data will be collected in a database in a single computer on site at the Regional Perinatal Center. This computer is password protected and reserved for use by care providers at the Perinatal Center that will be investigators for this study. The database will record specific patient identifiers including subject name and chart number. These specific identifiers will be removed at the completion of data collection prior to data analysis.