Nutritional advice in pregnancy

To assess the effects of advising pregnant women to increase their energy and protein intakes on those intakes, on gestational weight gain, and on the outcome of pregnancy.

The register of clinical trials maintained and updated by the Cochrane Pregnancy and Childbirth Group.

All acceptably controlled comparisons of nutritional advice, whether administered on a one-to-one basis or to groups of women.

Data were extracted by the author from published reports, and supplemented by additional information from trialists contacted by the author.

Four trials involving 1108 women were included. Advice to increase energy and protein intakes seems to be successful in achieving those goals, but the increases are lower than those reported in trials of actual protein/energy supplementation. Data concerning effects on pregnancy outcome are available only from one trial, and, given the fact that its analysis was based on individual women despite randomization by clinic, the calculated confidence intervals are undoubtedly too narrow. Moreover, the 'significant' reduction in preterm birth associated with advice is not consistent with the total absence of effect on mean gestational age. One trial found no reduction in the incidence of pre-eclampsia. No data have been reported on potential adverse effects that might accompany increased fetal size, such as an increased risk of prolonged labour or Caesarean section.

Nutritional advice appears effective in increasing pregnant women's energy and protein intakes, but the implications for fetal, infant, or maternal health cannot be judged from the available trials. Given the rather modest health benefits demonstrated with actual protein/energy supplementation (see the Cochrane review of 'Balanced protein/energy supplementation in pregnancy'), however, the provision of such advice is unlikely to be of major importance.