Infant formulas take two times longer for a baby to digest than breast milk. The slower digestion of infant formula can affect:

• Feeding frequency. Babies who take infant formula usually want to feed less often than babies who are breast-feeding.
• Sleeping patterns. Babies who take infant formula may sleep longer at night once they are about 2 months old. However, babies who are breast-fed usually catch up shortly thereafter, at about 3 to 5 months of age.
• Bowel movements. Infant formula causes formed, brown stools that have a noticeable odor. Breast milk causes loose, yellow stools that have less odor.