During pregnancy, a baby developing inside the womb receives all its nutrition from its mother. Therefore, advising women on their diet and providing food supplements in pregnancy may help babies to grow and thrive. This review of randomised controlled trials examined several aspects of dietary advice and supplementation and produced the following four findings.
(1) Providing nutritional advice resulted in an increase in the mother's protein intake, fewer preterm births in two trials involving 449 women and increases in birth head circumference in one trial involving 389 women.
(2) Giving the mothers balanced energy and/protein supplements was associated with clear increases in mean birthweight (11 trials, 5385 women) with fewer stillbirths (five trials, 3408 women) and fewer small-for-gestational age births (seven trials, 4408 women), but the impact on the long-term health of the baby was uncertain, including among undernourished women.
(3) High-protein supplementation: one trial involving 1051 women showed no benefit for women and potential harm for the baby.
(4) Isocaloric protein supplementations (i.e. balanced supplements in which the protein replaces an equal quantity of other nutrients, e.g. macronutrients, fat and carbohydrate): in two trials involving 184 women this intervention showed no benefit for women or their babies.
Providing nutritional advice or balanced energy and protein supplements to women during pregnancy may be beneficial; high-protein supplements and Isocaloric protein supplements given in to women in pregnancy may be unhelpful or harmful.