It is prescribed routinely to all newborns or babies under 1 yr of age along with calcium syrup. If you aren't so keen on it, u can give only vitamin D drops. Breast milk is deficient in vitamin D and hence it needs to be supplemented unless your baby is on top feeds. But make sure that the mother is taking her supplements as long as she is breastfeeding, so that the baby receives his/her share of supplements from her