Altered placental aging is recognized to be a potential mechanism in the pathophysiology of a scope of pregnancy complications related to placental dysfunction. Several studies have found that premature aging of the placenta is associated with preeclampsia, low birth weight, stillbirth, and preterm birth. The biological age of a tissue can be estimated with high accuracy using DNA methylation markers. This “clock” is particularly valuable in studies of placental aging because traditional histopathological examination and telomerase homeostasis markers may not capture subtle aging alterations and premature cellular senescence caused by DNA damage due to oxidative stress. Cellular oxidative stress within the placenta leads to increased release of several factors into the maternal circulation. Therefore, biomarkers that the placenta excretes into the maternal circulation may give early signals of pathological changes in a prematurely aging placenta. Biomarkers of oxidative stress, inflammation glycemic status will be measured in maternal plasma from the NICHD Fetal Growth study.