Stunting is a problem the world over.
Stunting is being short for your age. It is defined as a child more than two standard deviations below the National Center for Health Statistics chart of average heights for their age. Of course, a child may be short simply because both his parents carried genes for shortness.
However, malnutrition during childhood causes most of it, including malnutrition during fetal development brought on by the malnourished mother. According to the UN, about 165 million children under 5 years of age, or 26% of the children in the world, were stunted in 2011.
What role does vitamin D deficiency during late pregnancy play in stunting? Recently, a randomized controlled trial answered some of those questions.
Roth DE, Perumal N, Al Mahmud A, Baqui AH. Maternal Vitamin D3 Supplementation during the Third Trimester of Pregnancy: Effects on Infant Growth in a Longitudinal Follow-Up Study in Bangladesh. J Pediatr. 2013 Aug 30.
The authors gave 35,000 IU/week of vitamin D3 to 80 women during their third trimester of pregnancy and placebo to another 80 pregnant women. Then they measured the infant’s height at various ages after birth. As is standard care in Bangladesh, the infants received no vitamin D supplements. The cord blood at birth was 15 ng/ml in the placebo group and 41 ng/ml in the supplemented group.
The infants whose mothers took vitamin D grew an average of 1.1 cm taller than did the infants whose mother took placebo. Among term infants, mean head circumference at birth was significantly greater in the vitamin D group. While they didn’t give the numbers, the authors reported the two groups of infants became similar with respect to their 25(OH)D distributions around 4 months of age.
In longitudinal analyses, height significantly accelerated during the first 4 weeks in the vitamin D group compared with placebo, followed by progressive growth faltering in both groups from about 2 months of age onward. However, that maternal vitamin D supplementation resulted in a near halving of the prevalence of stunting.
What would be the prevalence of stunting if the mothers took 35,000 IU/week throughout pregnancy and not just in the third trimester? What would be the prevalence of stunting if all the infants all got 1,000 IU/day of vitamin D? We just do not know, but this trial has made clear that vitamin D is crucial during pregnancy for proper growth and development.