Effects of energy and protein intakes on pregnancy outcome: an overview of the research evidence from controlled clinical trials.

This overview summarizes the evidence from controlled clinical trials bearing on the effects of energy and protein intakes during gestation on the outcome of pregnancy, based on meta-analyses of reports contained in the Oxford Database of Perinatal Trials. Trials of nutritional advice to increase energy and protein intakes, and of balanced energy and protein supplementation, have demonstrated only modest increases in maternal weight gain and fetal growth, even in undernourished women, and no long-term benefits to the child in terms of growth or neurocognitive development. Neither balanced isoenergetic protein supplementation nor high-protein supplementation appears beneficial to either mother or infant and may even impair fetal growth. The same can be said for energy and protein restriction in pregnant women who are overweight or exhibit high weight gain. Future trials should concentrate on prevention of preterm birth and fetal and neonatal death; such trials will require substantially larger sample sizes than those used in the past.