2.2.1 Maternal-fetal transfer by birth: Given the fact that Canadian women do not consume enough milk (15, 16), it is not surprising that over 1/3 of infants are born already deficient in vitamin D. In Manitoba, the PI has documented that 36% of infants from white or non-white parents are deficient in vitamin D at birth, defined as a serum 25(OH)D below 27.5 nmol/L, with 46% of their mothers themselves having values < 37.5 nmol/L (6). In that study, 20% of white infants were deficient, and as a group 60% of First Nations, Asian, Filipino and Black infants were deficient. This suggests that vitamin D deficiency is not uncommon, particularly in non-white women and their infants (6, 19-22). Likewise season of birth (19) and ethnicity (6) are important factors to consider in defining how much vitamin D is required to achieve and maintain target values for 25(OH)D in infants.