Fetal growth abnormalities, such as macrosomia and intrauterine growth retardation, are an important cause for increased perinatal mortality in the United States. Toward this end, accurate fetal weight determinations are very important for guiding prenatal care. Three-dimensional ultrasound is a recent technology that provides a new way to evaluate the fetus. This technique allows one to arbitrarily scan through a digital ultrasound volume dataset, visualize organs from different perspectives, and render anatomical features through computer processing. It also allows the retrospective measurement of distances and volumes even in the physical absence of the patient.
This protocol consists of two study arms and emphasizes the ability of 3D ultrasound to reliably measure fetal soft tissue as an index of generalized nutritional status. The longitudinal arm will enroll 400 pregnancies to allow the use of 2D and 3D ultrasonography for characterizing serial growth patterns of sonographic parameters throughout pregnancy. This approach compares ultrasound measurements or birth characteristics to individual growth standards specified by Rossavik prediction models. After delivery, a maximum of 329 newborn infants, resulting from the same pregnancies, will have correlative photographs and measurements of their head, abdomen, thigh, skin folds, weight, and crown-heel length taken to classify growth outcome. Noninvasive air displacement plethymography will be used to measure neonatal percent body fat and lean body mass after delivery. Infant body composition data will allow the precise classification of neonatal growth outcome for subsequent correlation to prenatal sonographic studies. The cross-sectional arm of this protocol will allow sonographic studies of 2,577 fetuses with similar correlative neonatal evaluation of 1,212 infants for a total of 3,789 subjects. The results will be used to develop a new fetal weight estimation models that combine 2D and 3D sonographic parameters to improve accuracy and precision of these predictions. A maximum of 50 newborns from this cross-sectional arm will also be re-evaluated for infant body composition at 1 and 2 weeks following delivery to document changes in percent body fat and fat-free mass. Therefore, the subject recruitment ceiling would be (2,577 mothers + 1,212 infants) + (400 mothers + 329 infants) or 4,518 total subjects for this Protocol.