The american academy of pediatrics recommends that all infants and children, starting shortly after birth, have a minimum daily intake of 400 iu of vitamin d. infants are likely to require supplemental vitamin d because

The American Academy of Pediatrics recommends that all babies receive vitamin D supplementation (400 IU per day) due to decreased sunlight exposure and an increase in rickets.

Babies need this due to lack of sunlight exposure and is highly recommended if they're breastfed.

Ithink its c hope it : )