Prenatal Origin of Childhood Overweight, Obesity and Insulin Resistance, with Special Emphasis on Maternal Diabetes, Excessive Weight, Nutrition and Hormone Imbalances

Overweight at childhood, adolescence and adulthood is now considered a world-wide epidemic. A variety of preventive and therapeutic measures are being developed with partial success. Since the pioneering studies of D.J. Barker linking maternal famine in pregnancy to long-term undesira-ble effects on the offspring, the "metabolic syndrome", that stems from long-lasting epigenetic changes, it became evident that there are many undesirable events which affect in utero fetal growth and development and persist postnatally, through childhood and adulthood. The purpose of this review is to discuss the prenatal factors that may have long term effects on postnatal weight gain and obesity that are major contributors to this epidemic of "overweight and obesity". Understanding these factors might help us find more effective preventive measures. The list of these prenatal undesired factors is connected to some maternal diseases that affect fetal growth: pregestational and gestational diabetes, p-pregnancy maternal overweight and obesity, excessive weight gain in pregnancy, placental dysfunction and maternal hormonal imbalances in pregnancy. They all affect fetal growth often causing excessive fetal growth (macro-somia) and sometimes diminished growth (small for gestational age). Due to long lasting epigenetic changes, they often lead to insulin re-sistance that induces metabolic alterations which may lead to increase in food intake, overweight and obesity. Studies also demonstrate that in-creased exposure in pregnancy to some teratogens, like endocrine dis-ruptors and cigarette smoking may affect fetal growth and adiposity, in-ducing epigenetic changes which lead to postnatal insulin resistance, overweight and obesity. Normalization of intrauterine fetal growth might open a new area of preventive measures for childhood obesity that might be more effective than the currently used dietary measures. In addition, early diagnosis of insulin resistance and proper treatment in addition to diet and exercises may be a more effective approach.