Effects of maternal nutrition on fetal and neonatal reproductive development and function.

Maternal undernutrition and, under certain circumstances overnutrition, before or during pregnancy or during early postnatal life can alter reproductive function of the offspring. Effects can be exerted at many stages of development, from prior to conception until after birth and may be expressed at the time of the nutritional insult or later. Since patterns of development differ between species, it is probably more appropriate to consider effects in relation to a stage of development rather than relative to the time of birth. Effects exerted at one stage of development may be expressed later, even if the nutritional influence is no longer present. The signals by which maternal nutrition affects the offspring must be related to maternal nutritional state and must have the capacity to reach the embryo, to be 'read' by it and to modify expression of selected genes. It is suggested that single nutrients and/or metabolites are unlikely to have direct impacts on the pattern of development of the reproductive system and it is postulated that multiple endocrine and metabolic signals are involved. Whilst it has been shown that many components of the hypothalamic-pituitary-gonadal system are modified by early life nutritional influences, understanding of the mechanisms through which these effects are exerted remains limited.