The evidence reviewed suggests the interesting hypothesis that autism risk could be significantly reduced through use of vitamin D supplements; to avoid D deficiency in parents before conception, in mothers during their pregnancies, and in infants after they are born.  There is also the possibility that maintaining adequate serum 25(OH)D levels even before conceiving might help reduce risk of autism by reducing the rate of de novo mutations. These hypotheses deserve careful testing.

There is also evidence that maternal vitamin D deficiency is an important risk factor for many other adverse pregnancy and birth outcomes such as preeclampsia1, primary Cesarean section2, schizophrenia3, and several other adverse outcomes4

Work by Bruce Hollis and colleagues has shown that it is important for pregnant and nursing women to have high circulating values of vitamin D in addition to sufficient serum 25(OH)D levels (>40 ng/ml) in order for the fetus or infant to convert vitamin D to 25(OH)D [Taylor, 2008].  To achieve these outcomes, oral intake of as much as 6000 IU/day of vitamin D3 may be required5. In a randomized controlled trial using 6000 IU/day of vitamin D3 for pregnant and nursing women, no adverse effects such as hypercalcemia were observed [Hollis & Wagner, 2009]. It would be advisable to measure serum 25(OH)D levels prior to supplementing with high vitamin D doses as well as after such dosing for a month or two as solar UVB is an important source of vitamin D and there is considerable individual variation in serum 25(OH)D level with respect to oral supplementation.  See the graph at

Page last edited: 17 May 2011


  1. Bodnar, L. M. Catov, J. M. Simhan, H. N. Holick, M. F. Powers, R. W. Roberts, J. M. Maternal vitamin D deficiency increases the risk of preeclampsia. J Clin Endocrinol Metab. 2007 Sep; 92 (9): 3517-22.
  2. Merewood, A. Mehta, S. D. Chen, T. C. Bauchner, H. Holick, M. F. Association between vitamin D deficiency and primary cesarean section. J Clin Endocrinol Metab. 2009 Mar; 94 (3): 940-5.
  3. McGrath, J. J. Burne, T. H. Feron, F. Mackay-Sim, A. Eyles, D. W. Developmental vitamin D deficiency and risk of schizophrenia: a 10-year update. Schizophr Bull. 2010 Nov; 36 (6): 1073-8.
  4. Kaludjerovic, J. Vieth, R. Relationship between vitamin D during perinatal development and health. J Midwifery Womens Health. 2010 Nov-Dec; 55 (6): 550-60.
  5. Hollis, B. W. Vitamin D requirement during pregnancy and lactation. J Bone Miner Res. 2007 Dec; 22 Suppl 2V39-44.