Your newborn baby - how big is his stomach?

Well, do you know?

Most women will probably estimate it to be much larger than it really is. In truth, the size of a newborn baby's stomach is about the size of a hazelnut, or small glass marble, with a capacity of 5-7ml/cc per feeding. This is not a lot. This is not much at all. But the fact is that, many women who have just given birth do not know this, with what consequence? Some (or many) are pressured into "topping off" with formula to "ensure" the baby got enough. This in turn, becomes a self-fulfilling prophecy because the baby will nurse less at the breast, the mother's breasts will not receive due stimulation, and if supplementation continues, the breasts are tricked into thinking there is little to no demand for milk. On the other hand, some mothers with babies in the NICU who have to resort to pumping get frustrated because they are led to believe that the teaspoon of colostrum they worked so hard to express, is simply "not enough"....The size of the baby's stomach also has as a result the very frequent feedings breastfed babies have. 

On day three, the baby's stomach has grown to the size of a shooter marble, which can approximately hold 22-27 ml/cc or about 1 ounce, of milk at any given feeding. Take a look at your baby's fist and you'll get a good idea of how big his stomach is.

By day 10, your newborn's stomach is still very small, accommodating about 45-60 ml/cc or about 1.5-2 ounces per feeding. This is roughly the size of a walnut or a golf ball. This coupled with the quick and easy digestion of breast milk not surprisingly makes for a frequently feeding breastfed baby. About 8-12 feedings per 24 hours to be exact. (1)

It is sad to say, though, that I have personally heard and experienced hospital staff nearly threatening and filling the new mother with anxiety about not being able to produce enough colostrum for her very hungry baby. With their jittery, uneasy and (perhaps well-intentioned) worrisome tone of voice, they constantly badger the mother about the fact that if the baby does not drink, the baby cannot pee.. and the baby must pee or else...

Touching on this subject very briefly, since the input of milk is so small, wouldn't that automatically mean they can only pee so much? This is very true. On the first day of life, a healthy term infant will wet one diaper, increasing with the number of days until mom's milk comes in ( so, 1 wet diaper on day one, 2 wet diapers, on day two, etc)

According to Scammon RE, Doyle LO. Observations on the capacity of the stomach in the first ten days of postnatal life. Am J Dis Child 1920; 20:516-538.

·         day 1 - .25 oz

·         day 2- .46 oz

·         day 3 - .96 oz

According to another study (2) breastfed babies regained their birth weight quicker or just as quick as their mixed feeding counterparts, which busts the myth of insufficient milk. In the study Group A represented exclusively breastfed infants and Group B represented the control group of mixed feedings (4 times daily from the breast - 6 times formula). The study goes on to note:  "By the sixth day after birth, the weight increment in Group A is even higher than the newborns in the control group. Basing on the rate of increment, the average time required to regain their birth weight is 9.36 days in Group A, slightly less than 9.44 days in the control group."

Equipped with this information may you resolve to continue providing your baby with colostrum fully confident that you are able to fully nourish your baby from your breast. Don't let (well-meaning or not) hospital staff bully or frighten you into giving up and supplementing before you truly got the chance to breastfeed. How else has all of humanity survived on just colostrum in the first days of life...?

Notes: 

(1) Silverman, WA, ed.  Dunham's Premature Infants, 3rd edition. New York: Hoeber, Inc., Medical Division of Harper and Brothers, 1961, p. 143-144.

(2) Wang,Y et al:  Preliminary Study on the Blood Glucose Level in the Exclusively Breastfed Newborn, J Trop Peds 1994, 40:187-88.