Updated April 09, 2014
It seems like a simple enough question. Unfortunately, the simplest answer sometimes isn't useful.
A more practical answer is that your baby may need to take a vitamin supplement if:
All babies actually need vitamin D. In fact, the American Academy of Pediatrics, in its clinical report, Prevention of Rickets and Vitamin D Deficiency: New Guidelines for Vitamin D Intake, recommends that all children, starting in the first few days of life, receive at least 400 IU of vitamin D each day.
Baby formula is supplemented with vitamin D. So babies drinking at least 1 liter (about 33 ounces) of formula each day don't need any extra vitamin D. However, babies who are exclusively breastfed, breastfed and partially fed with infant formula, for fully formula fed, but who don't drink 1 liter of formula a day, do need it and can get it by taking a daily vitamin that contains vitamin D.
Remember that just because babies don't get enough vitamin D from breastfeeding, that is not a reason to supplement with formula or not to breastfeed. It just means that you should give your child a vitamin with vitamin D such as:
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