Impact of maternal nutrition on ovine foetoplacental development: A review of the role of insulin-like growth factors

The intrauterine environment may impact the conceptus (embryo/foetus and associated extra-embryonic membranes) during ‘critical periods’ of development, when rapid cell divisions occur in various tissues of the body, and may alter expression of the foetal genome, and this may have lifelong consequences; a phenomenon known as foetal programming. Among intrauterine environmental factors, nutrition appears to play the most critical role in influencing placental and foetal growth. Changes in maternal nutritional status during pregnancy often results in permanent structural and functional deficits in foetal, as well as, postnatal growth of animals. Maternal undernutrition or overnutrition during pregnancy can impair foetal growth. Alterations of the insulin-like growth factor cascade are speculated to play a significant role in intrauterine nutrition-associated compromised foetal growth and foetal programming. Insulin-like growth factors, IGF-1 and IGF-2 are nutritionally sensitive proteins that are believed to modulate foetal and placental growth. The role of these growth factors in nutrition-associated deficits in ovine foetal and placental growth is the subject of this review.