Vitamin D supplementation depends on whether you breastfeed your baby or how much formula with vitamin D your baby drinks.

These are the guidelines from the American Academy of Pediatrics for vitamin D for babies:

• Breastfed or partly breastfed babies need 400 international units (IU) of liquid vitamin D a day. This should start soon after birth. Babies need this amount of vitamin D supplement until weaned or until they drink 32 ounces (about 1 liter) a day of formula with added vitamin D.
• Formula-fed babies getting less than 32 ounces (about 1 liter) a day of formula with vitamin D need 400 IU of liquid vitamin D a day. This should start soon after birth. Babies need this amount of vitamin D supplement until they drink at least 32 ounces (about 1 liter) of formula with added vitamin D a day.

When giving your baby liquid vitamin D, make sure not to give more than the suggested amount. Read the instructions that come with the supplement. Use only the dropper that comes with it.

While breast milk is the best source of nutrients for babies, it likely won't give them enough vitamin D. Too little vitamin D can cause a softening and weakening of bones called rickets.

The sun is a good source of vitamin D. But the American Academy of Pediatrics says to keep babies younger than 6 months out of direct sunlight. Supplements are the best way to make sure babies get enough vitamin D.

As babies get older, foods that have vitamin D can help babies get enough. Foods may have added vitamin D, or it is found naturally in foods such as fatty fish like salmon and egg yolks. Drinking whole milk after age 12 months can also help with vitamin D levels.

If you have questions about your baby's need for vitamin D supplements, talk to your baby's healthcare professional.