A newborn typically eats every two or three hours whether he is breastfed or bottle fed with formula. As he grows, your newborn's nutritional needs change, particularly when he goes through growth spurts. These demands mean he needs an increase in the amount of food he receives. Several factors help you determine when your baby needs additional formula or breast milk to support his growth and development. An awareness of the signs allows you to keep up with the changing dietary demands of your baby.
Multiply your newborn's weight by 2.5 to get an estimate of the number of ounces she should eat each day. For example, an 8-lb. baby should eat about 20 oz. each day. If your baby eats about 10 times per day, each bottle should contain about 2 oz. of formula or breast milk. Recalculate that estimate as your baby gains weight to know when to increase the amount.
Offer a newborn 1 to 2 oz. of formula at a time. After the first week, increase that amount to between 2 and 4 oz. per feeding.
Monitor your newborn's weight gain. If he isn't gaining weight properly, he may need more formula or breast milk. Contact your newborn's doctor if you are concerned about lack of weight gain.
Track your newborn's wet diapers. Look for at least five or six wet diapers each day to indicate that she is getting enough to eat. Fewer wet diapers may mean she needs more to eat.
Increase feedings if your baby finishes a bottle faster than normal and still acts hungry when the formula or breast milk is gone. If still hungry, your newborn may root around or look for the bottle when the food is gone and you take the bottle away.
Watch your baby's demeanor at the end of a feeding session. Look for signs of contentment, relaxation and satisfaction to indicate that he is getting enough to eat. If he doesn't seem satisfied, increase the amount of formula or breast milk.
Look for signs of hunger shortly after a feeding session or sooner than expected for the next feeding. Signs of hunger include sucking, lip smacking, rooting or hands at the mouth. Crying is a later sign of hunger.
Increase feeding amounts during the usual periods of increased growth. These growth spurts typically occur around 10 days, three weeks, six weeks, three months and six months of age, according to the website, Babycenter.