Two related and growing bodies of research suggest that women with eating disorders (EDs) experience pregnancy complications more frequently than healthy women, and individuals with EDs are more likely than healthy individuals to have a history of birth complications themselves. More specifically, women with EDs have a higher rate of perinatal complications, cesarean deliveries, and post-partum depression. Moreover, their offspring tend to weigh less than offspring of women without EDs and experience more problems with growth and development. In terms of the second point above, prospective epidemiological research suggests that individuals with anorexia nervosa (AN) are more likely to have been born prematurely, have been small for gestational age (SGA), and have suffered from cephalohematoma. Both bodies of research suggest that perinatal events may be critical to the etiology of EDs and that the perinatal period may be of particular relevance in further elucidating etiological factors in EDs. Although the mechanism of actions is not yet clear, individuals with threshold or subthreshold ED symptoms may increase their risk of adverse pregnancy outcomes by restricting food intake around the time of conception. Indeed, recent animal studies have shown that moderate maternal undernutrition around the time of conception can increase the risk of preterm birth. Together, these studies suggest a cycle of risk, that could be influenced by both genetic and environmental factors, that may flow through generations to perpetuate risk for EDs in families. No study has yet been able to study this cycle of risk in a single population-based sample. We propose to explore the impact of EDs, related behaviors and nutrition during the perinatal period on pregnancy outcome in a sample of 100,000 births in Norway. The Norwegian Mother and Child Cohort Study (Mor & barn undersokelsen) is a prospective population-based study of 100,000 births to 100,000 mothers and 80,000 fathers in Norway. Assessments are extensive including blood for DNA, psychosocial factors, infections, medication use, nutrition, life styles, occupational exposure, use of health services, substance abuse, socioeconomic factors, and chemical and physical factors in the environment. Health variables include fetal ultrasound, maternal and paternal history, and health outcomes for the mother and child detected during and after pregnancy. EDs and related behaviors are assessed at 17 weeks pregnancy and 18 months post partum. This study will provide prospective data on the risk to pregnancy outcome and child development associated with EDs in the mother independent of the effects of depression, anxiety and nutrition. [unreadable] [unreadable]