Maternal diet and fetal substrate provision

Abstract

The importance of maternal diet on fetal substrate provision has been reviewed. There is significant variation in the energy requirements for pregnancy between populations and individuals. This is particularly noticeable when contrasting and comparing studies from the developed world with those from developing countries. The effects of energy deficit have been illustrated with reference to famine. The somewhat paradoxical situation relating to excess requirements has been demonstrated by reference to excess protein intake and the consequential decrease in birthweight. Further evidence of adverse effects of excess substrate provision is provided by studies of pregnancy complicated by diabetes. Qualitative as well as quantitative aspects of maternal diet have been discussed. Current evidence suggests that altering the maternal nutrition influences the substrate mix. In the second half of pregnancy insulin resistance occurs. Insulin's actions on maternal metabolism affect the provision of the main fetal substrate, glucose, but also influence the availability of other substrates. Dietary modifications can result in a state of decreased insulin resistance and this could have important clinical consequences in the obese gravida and in diabetic pregnancy. There have also been suggestions that dietary manipulation may also influence the occurrence of certain adult diseases if Barker's hypothesis is maintained. Despite recent additions to the literature controversy still exists with regard to most aspects of fetal substrate provision and further research is needed to address some of these uncertainties.