In addition to the increase in obesity in adult and children, there has been a significant increase in birth weights over the last 2 decades. Based on our preliminary data, maternal pre-gravid obesity is the strongest risk factor for neonatal as well as adolescent obesity. The long-term goals of our research are to examine therapeutic strategies to decrease fetal adiposity. Obesity and pregnancy are both insulin resistant conditions associated with chronic low-grade inflammation. Therefore, we hypothesize that n-3 PUFA dietary supplements during pregnancy will act as insulin sensitizers decreasing peripheral insulin resistance and inflammation. If correct this mechanism should decrease availability of maternal nutrients to the fetus and subsequently reduce adiposity at birth. We plan a prospective randomized double blind control trial of n-3 PUFA supplementation and placebo in overweight/obese women, with a previous cesarean delivery, initiated in early pregnancy and maintained throughout pregnancy. This proposal has two specific aims. Specific aim 1 is to evaluate the effect of n-3 PUFA supplementation on maternal insulin sensitivity. Measures of maternal insulin sensitivity and lipid metabolism will be made using the ISogtt, indirect calorimetry body composition (BODPOD) and plasma lipid profile at baseline and after dietary intervention.