Increases in macronutrient consumption during pregnancy can lead to increased birthweight

Giving pregnant women in the developing world a daily supplement containing 10 vitamins and five minerals could help increase the birthweight of their babies, concludes a study published online by The Lancet.

A third of global deaths happen in children younger than 5 years; most occur in the neonatal period – the first four weeks of life. Low birthweight (less than 2500 g) underlies many of these deaths. Around 25 million low-birthweight infants are born every year. Maternal nutritional status is closely linked with foetal weight. Increases in macronutrient consumption during pregnancy can lead to increased birthweight.

David Osrin (Institute of Child Health, UK) and colleagues did a trial to test whether multiple micronutrient supplementation at one recommended daily allowance would increase birthweight and help prolong pregnancy to full term. 1200 women from Nepal, who had reached up to 20 weeks of pregnancy, were recruited onto the trial between August 2002 and October 2003. Women were randomly assigned to receive either a supplement containing 10 vitamins (vitamin A, E, D, B1, B2, B6, B12, C, niacin, folic acid) and five minerals (iron, zinc, copper, selenium, iodine) or the nationally advised tablets containing iron and folic acid once daily for an average of 160 days. Birthweight data for 1052 babies was available in the analysis. The average birthweight was 2733 g in the control group and 2810 g in the intervention group, representing an average difference of 77 g and reduction in the prevalence of low birthweight by 25%. The length of pregnancy was 1·5 days longer in the intervention group than in the control group but that result was not significant. The difference in the mean birthweight was more marked in female infants (108 g compared with 44 g in males) and in infants of mothers whose body mass index was 18·5kg/m² or more (83 g compared with 54g in those with a body mass index of less than 18.5 kg/m²).

Dr Osrin concludes: “Our tentative finding of a differential effect of the supplement is interesting. The effect of multiple micronutrients on foetal weight seems to have been enhanced in female infants, in births of higher order, and in babies of women with greater body-mass index. The public-health implications of our findings await confirmation by the results of other studies currently underway.”