The NICHD conducts studies focusing on child health and human development and as such has generated and will continue to generate a collection of human biospecimens pertaining to these research activities. Fetal growth traits are significantly associated with adverse health outcomes including obesity, diabetes, and cardiovascular complications. Both genetic and non-genetic factors influence fetal growth. A genetic approach to study the determinants of fetal growth and interactions between genetic and environmental factors is critical for elucidating mechanisms underlying the links between skeletal growth, birth weight and adult chronic diseases, and to gain new insights into genetic contributions to fetal growth differences among individuals and ethnicities. A clear understanding of the genetic and environmental factors that influence fetal growth will give insights into mechanisms underlying the associations between fetal growth and chronic disease in later life, and can point to early intervention targets. Specimens from the Fetal Growth study were using for DNA from multi ethnic populations