Normal fetal growth is a critical component for a healthy pregnancy and for ensuring the health and well-being of infants throughout childhood and adolescence. Abnormal fetal growth is known to occur in pregnancies complicated by hypertensive disorders and gestational diabetes, among other gravid diseases. Identifying the patterns and timing of abnormal fetal growth in relation to specific pregnancy complications and their timing of onset can inform clinical management. One promising area of research suggests that changes in fetal soft tissue may be the earliest changes that occur in pathologic growth. Three-dimensional volume assessments may be used to detect changes in fetal lean mass, fat mass, and organ size that result from pathologic growth earlier than conventional 2D measures.
The Fetal 3D Study involves ultrasound measurements of images and volumes collected in the NICHD Fetal Growth Studies, a prospective cohort of 2,334 low-risk, normal weight women divided among four self-identified race/ethnicity groups: 614 non-Hispanic White, 611 African American, 649 Hispanic, and 460 Asian women. Two other cohorts comprising obese women (n=468) and women with dichorionic twin pregnancies (n=171) were also enrolled.
The overarching research aim of the Fetal 3D Study is to both establish standards for fetal body composition and organ volumes by race/ethnicity and to understand the relationship between gravid diseases and longitudinal changes in fetal body composition (subcutaneous fat, lean mass) and organ measurements (in singletons) over the course of pregnancy, thereby, complementing available data for the Cohort. A second aim is to investigate potentially modifiable factors (including maternal BMI, weight gain, longitudinal changes in maternal body composition, nutrition and lifestyle factors) associated with changes in fetal body composition and organ volumes, with the goal of identifying intervention targets for adverse outcomes among women and the fetuses they carry. A third aim is to explore the association of biomarkers with longitudinal changes in fetal body composition and organ volumes. A collection of measurements of lean and fat body composition and volume data as proposed in the present study offers great potential of investigating associations of a wide spectrum of pregnancy complications and longitudinal changes in fetal body composition as well as visceral organ size.