A. Although we usually talk about growth spurts and breastfed babies, there is no reason to think it doesn't happen to formula fed babies too. The main difference is that instead of having to breastfeed more frequently for a few days to increase their breast milk supply to meet their baby's increased demands, a baby fed formula can simply be given a little extra formula.
And that may be what you need to do.
Four months is a common time when infants have growth spurts, but it is important to recognize that they can happen at any time. That is why there are few real 'rules' on feeding babies. You often have to play it by ear and feed them based on their demands.
How much formula should your baby be eating? You can use this handy tip from The American Academy of Pediatrics that 'your baby should take in about 2 1/2 ounces of formula a day for every pound of body weight.' So if he is about 13 pounds, then on average, you would expect him to be eating about 32 ounces of formula each day. And if he is sleeping for a good 8 hour stretch at night, then that would be about 6 ounces of baby formula every 3 hours while he was awake.
Besides a growth spurt, another reason why an infant might want to eat more often during the day could be that he is sleeping longer at night. If he was getting up 2 or 3 times at night to eat and is now just up once or is sleeping all night, then he may be eating more often during the day to make up for those calories he isn't getting at night anymore. Again, like with a real growth spurt, you would usually just feed him more at each feeding to try to stretch him back out to 3 hours between feedings.
Another thing to consider is that some babies are ready to start cereal at 4 months, although we usually recommend waiting until a baby is closer to 6 months old. A sign that you might need to start an iron fortified infant cereal before 6 months might include that you are already feeding your baby more than about 32 ounces and he just isn't getting satisfied.