"They need to remember to give their babies vitamin D," Abrams said, but he also noted that few states provide the supplements to parents.
As Greer points out, the cost of a month's supply is not expensive, at $7 or $8 for a month's supply, but Abrams said even that could pose a problem.
"$8 to $10 is a cost some people just are not going to spend."
But avoiding rickets may not be the only reason to get those supplements. Another motive for the revised guidelines, according to the AAP, is to build up the body's defenses.
"New evidence supports a potential role for vitamin D in maintaining innate immunity and preventing diseases such as diabetes and cancer," write the authors in their abstract.
But evidence for that is less clear.
"The evidence is not real solid, but sufficient to err on the side of safety," said Thomas M. Badger, chairman of the department of physiology at the University of Arkansas for Medical Sciences.
Badger noted that vitamin D deficiency in children has been understudied, and short of full-blown rickets, physicians do not know much about the condition.
"In children, short of having clinical rickets, we don't really know what constitutes vitamin D deficiency and how severe it is," said Abrams.
While he worries that some will misinterpret the committee's new guidelines as an attack on breast milk, Abrams said he hopes that will be avoided. He said that while breast milk is a good source of nourishment for infants, it was never designed to be a source of vitamin D.
"The message we always try to give is that giving vitamins to your babies is in no way saying that breastfeeding isn't adequate," Abrams said.