The aim of my postdoctoral research project was to study the effects of maternalplacental-fetal (MPF) biological stress markers during pregnancy on outcomes related to obesity risk in children. I had the unique opportunity to capitalize on the availability of a cohort of children whose mothers participated during their index pregnancy in a research project at the University of California, Irvine. Prenatal data (including biological, fetal biometric, maternal biophysical, behavioral sociodemographic and psychosocial factors) has been collected prospectively and serially over the course of pregnancy from mothers of these subjects in NIH founded projects. In the present study, we focused on the association between MPF biological stress markers and obesity related health outcomes. We were successful in recruiting 189 children from the original pregnancy cohort back into the study, with assessment of child anthropometric measures. Furthermore, in a cohort of 107 newborns (term as well as preterm infants) we assessed body composition with dual energy X-ray absorptiometry (DXA). We found that MPF biological indicators of prenatal stress were independently associated with fetal as well as postnatal growth velocity and BMl at age 6-7 years. Furthermore, in a cohort of newborns, higher adiposity at birth was associated with the severity of prematurity, and there was a U-shaped function between birth weight and percent fat mass at birth: In normal birth weight infants, there was a positive association between birth weight and global percent fat mass, whereas in infants born with a low birth weight (< 2500g), higher global percent fat mass was predicted by lower birth weight. Taken together, our findings support a significant and independent role of the intrauterine environment on fetal and postnatal growth and obesity risk. The intrauterine period should become a focus of public health initiatives, to ultimately develop and test interventions to prevent, minimize or reverse the risk of a child becoming obese as a consequence of the exposures she or he experienced during intrauterine life, and thereby promote better health for our children and future generations.