Vitamins are organic compounds essential in small amounts for metabolic functions. Since they cannot be synthesized in the body they must be supplied with the diet. While fat-soluble vitamins cross the placenta by single and/or facilitated diffusion the water-soluble vitamins are actively transported with the exception of vitamin C. An adequate supply of fat-soluble vitamins to the fetus seems to be dependent on maternal blood levels during gestation. On the contrary, the transfer of water-soluble vitamins is relatively independent of the levels in maternal blood. Due to their immaturity preterm and low birth weight infants require higher dosages of some vitamins compared to healthy full-term newborns.