Supplementing Pregnant Women with Vitamin D to Prevent Newborn Deficiency
Newborns and breastfed infants are solely reliant on the nutrients that they receive via their mother. Nature attempts to provide good quality nutrition for most babies by making certain adaptations during pregnancy and lactation. Around 90% of fetal growth occurs in the second half of pregnancy when the average weight increases from 300 g at 20 weeks to 3300 g around the time of birth, and this is when maternal deficits are most likely to affect the baby’s growth. A series of small physiological changes that occur throughout pregnancy help women’s bodies make the changes necessary to support the high rate of growth of the fetus. For example, calcium absorption increases during pregnancy to help provide enough calcium for the developing skeleton (Diaz de Barboza, Guizzardi and Tolosa de Talamoni). However, as summarized by King, despite a wide variety of adjustments that the body is capable of making to ensure a good supply of all essential nutrients, a threshold exists whereby limitations in maternal diet result in deficiencies in the offspring. Perumal, Al Mahmud and Baqui describe a study in which they attempt to prevent newborn vitamin D deficiency by supplementing pregnant women during the third trimester of pregnancy.
Although not all nutrient deficiencies are able to be corrected during pregnancy (see our previous post on challenges in meeting the iron needs of pregnancy), vitamin D concentrations in mothers is highly correlated with that of their neonates and represents a nutrient for which supplementation is likely to be effective (see an early study from Hollis and Pittard). Various factors affect maternal vitamin D levels including the season, use of vitamin D supplements, and pregnancy weight gain, as studied in a recent research paper from Moon and co-workers. A recent open-label study from Rodda and colleagues found that relatively high doses of vitamin D (2000 to 4000 IU) in pregnant women could prevent deficiency in newborn babies. Another study from March et al. found that not all doses protected infants from vitamin D deficiency: the current RDA of 400 IU per day only protected half of infants supplemented from the second quarter of gestation into the early postpartum period, while a relatively high dose (2000IU per day) protected almost all infants from deficiency.
In the Perumal article, 160 pregnant women living in Bangladesh were supplemented with a high dose of 35000 IU per week (5000 IU per day) during the third trimester of pregnancy, or placebo. 115 infants returned for at least one visit after birth. Vitamin D levels were measured during the first week after birth, at 8 or 16 weeks, and at 24 weeks of age. The authors found that vitamin D levels in the first month were much higher in the supplemented group compared to the placebo group: no infants whose mothers were supplemented with vitamin D were deficient at 1 month of age, compared to 80% of the placebo group. For the remaining measurements at 2, 4, and 6 months, vitamin D levels in the supplemented group fell while vitamin D levels in the placebo group increased so that by the end of the study, around 5-6% of infants were vitamin D deficient. There was an effect of the season such that from mid-Spring until the rainy season, vitamin D levels tended to be higher in the older infants. Infants that received at least some infant formula were less likely to be vitamin D deficient.
High doses of vitamin D appear to be effective in preventing infant vitamin D deficiency. However, as shown by the clinical trial from March, the dose is important. The current RDA is not an effective dose: an amount between 1000 and 2000 IU per day, and up to 5000 IU per day, appears to reduce the infant vitamin D deficiency to close to zero. The safety of high dose supplementation needs to still be confirmed in large-scale, long term clinical studies.
Nandita Perumal, Abdullah Al Mahmud, Abdullah H Baqui and Daniel E Roth. Prenatal vitamin D supplementation and infant vitamin D status in Bangladesh. Public Health Nutrition, available on CJO2015. doi:10.1017/S1368980015003092.
Diaz de Barboza G, Guizzardi S, Tolosa de Talamoni N. Molecular aspects of intestinal calcium absorption. World J Gastroenterol. 2015 Jun 21;21(23):7142-54. doi: 10.3748/wjg.v21.i23.7142. http://www.ncbi.nlm.nih.gov/pubmed/26109800
Hollis BW, Pittard WB 3rd. Evaluation of the total fetomaternal vitamin D relationships at term: evidence for racial differences. J Clin Endocrinol Metab. 1984 Oct;59(4):652-7. http://www.ncbi.nlm.nih.gov/pubmed/6090493
King JC. Physiology of pregnancy and nutrient metabolism. Am J Clin Nutr. 2000 May;71(5 Suppl):1218S-25S. http://www.ncbi.nlm.nih.gov/pubmed/10799394
March KM, Chen NN, Karakochuk CD, Shand AW, Innis SM, von Dadelszen P, Barr SI, Lyon MR, Whiting SJ, Weiler HA, Green TJ. Maternal vitamin D₃ supplementation at 50 μg/d protects against low serum 25-hydroxyvitamin D in infants at 8 wk of age: a randomized controlled trial of 3 doses of vitamin D beginning in gestation and continued in lactation. Am J Clin Nutr. 2015 Aug;102(2):402-10. doi: 10.3945/ajcn.114.106385. Epub 2015 Jul 8. http://www.ncbi.nlm.nih.gov/pubmed/26156737
Moon RJ, Crozier SR, Dennison EM, Davies JH, Robinson SM, Inskip HM, Godfrey KM, Cooper C, Harvey NC. Tracking of 25-hydroxyvitamin D status during pregnancy: the importance of vitamin D supplementation. Am J Clin Nutr. 2015 Nov;102(5):1081-7. doi: 10.3945/ajcn.115.115295. Epub 2015 Sep 23. http://www.ncbi.nlm.nih.gov/pubmed/26399867
Rodda CP, Benson JE, Vincent AJ, Whitehead CL, Polykov A, Vollenhoven. Maternal vitamin D supplementation during pregnancy prevents vitamin D deficiency in the newborn: an open-label randomized controlled trial. Clin Endocrinol (Oxf). 2015 Sep;83(3):363-8. doi: 10.1111/cen.12762. Epub 2015 Apr 8. http://www.ncbi.nlm.nih.gov/pubmed/25727810