Significance: Pregnant women living in poverty often experience chronic stress, and consequently higher levels of stress hormones. In utero exposure to high levels of stress hormones can negatively affect the developing fetus and later, the infant's capacity for emotion and behavioral regulation. In this proposal we describe a developing program of research designed to reduce the negative impact of prenatal stress on infant health and development via nutritional supplementation of docosahexaenoic acid (DHA) during pregnancy. DHA is a long-chain polyunsaturated fatty acid member of the omega-3 fatty acid family. DHA is found in its highest concentrations in neural cell membranes, affecting receptor function, neurotransmitter uptake, and signal transmission. There is growing evidence that low levels of dietary DHA intake are associated with suboptimal response to stress and that DHA supplementation can modulate stress response. Aims: The goals of the proposed study are to explore whether DHA supplementation during pregnancy is associated with 1) a reduction in maternal perceived stress during pregnancy; 2) a more modulated maternal cortisol response to a stress stimulus during pregnancy, and 3) more optimal regulation of emotion and behavior in the infant. Approach: Sixty-five pregnant women living in inner-city poverty, who consume less than two servings of fish per week, will be randomly assigned to receive 450 mg/daily of DHA or placebo beginning at 16-20 weeks gestation through the end of pregnancy. Perceived stress, pregnancy related stress, stressful life events, anxiety, and depression will be assessed at baseline and at 24, 30, and 36 weeks of pregnancy and at 4 months post-partum. DHA levels will be assessed at baseline and at 36 weeks of pregnancy. Cortisol response to the Trier Social Stress Test will be measured at baseline, 24, and 30 weeks. At 4 months post-partum infant temperament, cognitive development and stress reactivity will be assessed in the laboratory. Investigators: This proposal stems from an National Institute of Mental Health R21 Translational Science Network on prenatal stress and mental health outcomes in the offspring. Three members of that network, Drs. Keenan, Carter, and Glover, are all funded investigators in the area of prenatal stress and child mental health, which is a prioritized area of exploratory research that could directly impact clinical care. They are collaborating on the present application. Innovation: This will be the first randomized controlled study of the effect of DHA supplementation on stress response in pregnant women living in inner-city poverty, and the first study of maternal DHA supplementation on emotion and stress regulation in their infants. Relevance: If DHA supplementation is associated with reductions in perceived stress, more modulated maternal cortisol response to stress, and more optimal emotional and behavioral regulation in the infant, even within the context inner-city poverty, then a comprehensive program of research on the mechanisms by which these associations evolve and the potential for broad-based prevention of poor developmental outcomes among children born to women living in poverty can be launched.