Gestational weight gain is positively associated with fetal growth, and observational studies of food supplementation in pregnancy have reported increases in gestational weight gain and fetal growth. This study assessed the effects of education during pregnancy to increase energy and protein intake, or of actual energy and protein supplementation, on energy and protein intake, and the effect on maternal and infant health outcomes. 149 reports corresponding to 65 trials were examined. This review provides encouraging evidence that antenatal nutritional education with the aim of increasing energy and protein intake in the generail obstetric population appears to be effective in reducing the risk of preterm birth, low birthweight, increasing head circumference at birth, increasing birthweight among undernourished women, and increasing protein intake. There was no evidence of benefit or adverse effect for any other outcome reported. Balanced energy and protein supplementation seems to improve fetal growth and may reduce the risk of stillbirth and infants born small-for-gestational age. High-protein supplementation does not seem to be beneficial and may be harmful to the fetus. Balanced-protein supplementation alone had no significant effects on perinatal outcomes. The results of this review should be interpreted with caution. The risk of bias was either unclear or high for at least one category examined in several of the included trials, and the quality of evidence was low for several important outcomes. Large, well-designed randomized trials are needed to assess the effects of increasing energy and protein intake during pregnancy in women whose intake is below recommended levels.
