It might be funny to think of your little duckling taking a daily multivitamin like a bodybuilder would, but believe it or not, the American Academy of Pediatrics recommends that babies who aren’t exclusively formula fed, and especially those under 6 months and exclusively breastfeeding, take a daily Vitamin D supplement.
Vitamin D is a very important nutrient for helping the body effectively absorb calcium and phosphorus, which means it’s a critical nutrient for building healthy bones.
Breast milk and formula both provide most of the nutrients a baby needs, but breast milk is lacking in Vitamin D, making a supplement important. The Mayo Clinic takes the position that all breastfed or partially breastfed babies should take 400 IU of liquid Vitamin D until they are weaned, and drinking more than 32 oz of D-fortified formula or cow’s milk each day. Formula-fed babies should take 400 IU of Vitamin D daily until they reach the 32 oz mark as well.
The sun is actually one of humanity’s main sources of Vitamin D, but infants and young babies are generally not (and shouldn’t be) in the sun for long enough to get a significant amount of Vitamin D this way.
Vitamin D comes in liquid form, and can be added to a bottle of breastmilk, so there’s no need to work out a safe way of getting a vitamin tablet into Baby.
You should speak with Baby’s doctor if you’re concerned about her Vitamin D intake, or before beginning to add any supplements to her diet. A full multivitamin, though, is generally not necessary for babies.