The Newborn Stomach Size Myth: It is NOT 5-7mL

Written by Jody Segrave-Daly, RN, IBCLC

As a veteran NICU, nursery nurse and IBCLC, I have taken care of and fed thousands of babies over the years.  When working in the special care nursery, babies were always fed according to their weight to determine their caloric requirements for intake amounts and optimal growth.

That is contrary to a lot of non-clinical discussion you’ll read out there on the internet about an infant’s intake needs, which suggest it’s mostly based on stomach size. So what’s fact and what’s fiction?

Calories and Feeding Amounts for Breast Milk, Formula, and Colostrum

What science tells us is that mature breast milk averages around 20 calories per ounce (~30ml) and bellysizeformula contains approximately 20 calories per ounce as well. Thus their per-milliliter (mL) calorie count is on average the same. Colostrum, a key substance that imparts passive maternal immunity to a newborn in the first few days of life if a mother breastfeeds, is lower in fat and carbohydrates than those two, and comes in around 17 calories per ounce (~30ml) (Guthrie 1989).

With that knowledge in mind, current hospital feeding protocols for formula-fed babies range from feeding 10-30 ml for newborns less than 6 pounds’ every 2-3 hours and feeding newborns over 6 pounds 10-30 ml every 3-4 hours on the first day of life.

But according to the Academy of Breastfeeding Medicine’s Supplementing Protocol, they suggest exclusively breastfed babies be fed 2-10 ml per feeding and they reference the infant stomach size according to outdated studies (1992 and 1920) to reflect intake volume. As you can see, that’s substantially less for a feeding than our current clinical protocols.

Fortunately, what they do say is that research is limited and more research is necessary to establish evidence-based guidelines that include infant weight, size of the stomach, age of infant, insensible weight loss. They also say an infant should be fed according to satiation, despite their guidelines. I expect that protocol will likely to be under review in the near future and refreshed with updated data and guidelines, as it was last updated in 2009, making it due for revision.

Turning to other popular breastfeeding education resources for new mothers that discuss infant intake needs and stomach size, you’ll find The Office of Women’s Health in the US, The Le Leche League, WIC programs, IBCLC’s, CLC‘s are also teaching mothers that their newborn’s stomach size is 5-7 ml on day one.

Why the volume difference between formula and breastfeeding newborns despite the same caloric amount? Why are hospitals able to feed an infant 10-30ml on day one if their stomach size is allegedly at most, 7ml? And where did the current idea of newborn stomach size (and with it, an “optimal” calorie amount) originate from?  I decided to find out.

The Myth of the Newborn Stomach Size: Where Did it Come From?

I started my research with my non-clinical hat on and turned to Google, since this is where my patients typically go first. When I did a Google search for newborn stomach sizes there were over 868 thousand links!  I was led to a plethora of visual images depicting newborn stomach size. Some of the most popular images were the belly ball models that lactation consultants wear on their lanyards so they can visually educate new mothers how big their newborn’s stomach size “is.”

Clinical hat back on, I dug into the science behind these belly balls. In the 2008 Journal of Human Lactation I found a published article that revealed a completely different utility for belly ball models. Marble/ball models are often used to represent newborn stomach capacity; however, their accuracy has not been determined:

“Measurement of infant stomach capacity has been attempted for over 100 years. Exact volumes cannot be standardized, but data suggest that anatomic stomach capacity and physiologic stomach capacity vary widely” and also, “it is important to note that because a wide range of feeding volumes on day 1(1.1-20.4 mL) and day 3 (13.1-103.3 ml) has been reported, and the reasons for these variances are unclear, it may be best to simply acknowledge that feeding volumes vary widely and like stomach capacity, do not lend well to visual representation given our current knowledge.”

Despite that qualification, new moms are inundated with images where there are a series of bottles filled with milk depicting the size of an infant stomach according to each day after birth, sometimes compared with fruit or different sized marbles and balls:

I continued to search for more resources and I found more recent research in 2013 from Dr. Nils Bergman who published this study, which says:

“There is insufficient evidence on optimal neonatal feeding intervals, with a wide range of practices. The stomach capacity could determine feeding frequency. A literature search was conducted for studies reporting volumes or dimensions of stomach capacity before or after birth. Six articles were found, suggesting a stomach capacity of 20 ml at birth.” 

stomachsize1-pptx

My concern as a long-time NICU nurse and IBCLC has always been why are mothers  taught universally that their exclusively-breastfed newborn baby only needs 5-7 mL of colostrum per feeding when clearly there is no scientific evidence that supports it (and why clinical experts currently feed infants more, based on science that is available)?Gastric emptying is complete in one hour into the small intestine which allows for milk volume to be more than 5-7 ml every 2-3 hours as recommended. 

So how often should exclusively breastfed babies eat?

There is no single right answer to this question because each baby has a different weight and unique calorie requirements. By just weight alone, a 6.6 pound baby has an average size stomach of 20mL on day 1 and would require 32.5 ml or 1.1 oz  in breast milk or formula every 2 hours to meet  their basic metabolic needs. But babies should also be fed by infant cue to satiation. In other words, if your baby is crying and crying after breastfeeding, an immediate medical exam is necessary to be sure the baby is not suffering from insufficient intake at breast when exclusively breastfeeding.

It’s time to ditch the belly models, update our breastfeeding education resources according to the current scientific resources  and practice science based infant feeding practices! Our babies are counting on us to keep them well-fed, meeting their metabolic needs with correct intake volume using the best and current infant feeding practices possible.


See below for additional resources:

The American Academy of Pediatrics’ Breastfeeding Guidelines

Helpful guide to safe infant feeding amounts from the American Academy of Pediatrics.

Helpful overview of infant feeding for the first month of life, from the American Academy of Pediatrics.

Guthrie, Helen Andrews. Introductory Nutrition. St. Louis : Times Mirror/Mosby College Pub., 1989

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