The Newborn Stomach Size Myth: It’s not 5-7 mL

Written by Jody Segrave-Daly, MS, RN, IBCLC

As a veteran NICU, nursery nurse, and lactation consultant, 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 and cumulative losses, to determine their caloric requirements for intake amounts and optimal nourishment. For example, term babies who are admitted to the NICU from complications of not receiving enough colostrum are immediately fed based on their weight, usually about 60-80 ml/kg/day (typically 15-30 ml) every 2-3 hours. When allowed to feed on demand, newborns will typically take increased volumes eagerly and demonstrate feeding satisfaction and comfort.

Why do some babies tolerate fasting before the onset of copious milk production and other babies do not? 


This is contrary to a lot of non-clinical discussions you’ll read out there on the internet in a plethora of mommy groups 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 (~30 mL) and formula milk 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).

#2 Why Fed is Best- CaloriesColostrum(1)

With that knowledge in mind, current hospital feeding protocols for formula-fed newborns 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 hours on the first day of life.

But according to the newly updated Academy of Breastfeeding Medicine Supplementation Protocol, they suggest exclusively breastfed babies are fed 2-10 ml per feeding and they reference the infant stomach size according to outdated studies (1992 and 1920) to reflect intake volume.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 hospital clinical protocols state. They also say there is no definitive research available and the amount of supplement given should reflect the normal amounts of colostrum available, the size of the infant’s stomach, and the age and size of the infant. The intake on day 2, post-birth is generally higher than day 1 in relation to the infant’s caloric demand. Based on the limited research available, suggested breast milk intakes for healthy, term infants their feedings should be based on satisfaction cues despite their guidelines. Unfortunately, this information contributes to additional confusion that already exists for parents.

Fortunately, what they do say is research is necessary to establish evidence-based guidelines on appropriate supplementation volumes for specific conditions and whether this varies for colostrum versus infant formula. Specific questions include the following:

Should the volume be independent of infant weight or a per kilogram volume? Should supplementation make up for cumulative losses, like we do in the nursery and NICU?

Many popular breastfeeding education resources for new mothers, also refer to inaccurate information by teaching mothers the stomach size is 5-7 ml on day one. This picture is from a mother who delivered this week in a Baby-Friendly Hospital. Imagine her confusion when her baby required additional amounts of supplementation to prevent hypoglycemia complications and no one could explain to her why her baby could comfortably tolerate more milk than what she was taught in this resource booklet.

A breastfeeding booklet for mothers in a BFHI hospital.

Why the volume difference between formula and breastfeeding newborns despite the same caloric amount? Why are hospitals able to feed an infant 10 – 30 mL 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.”

I was in disbelief knowing our most trusted breastfeeding experts were wearing and using, proudly I might say, very inaccurate information. I quickly began to understand that ‘belly bead’ models are lucrative merchandise to sell!  

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.” In addition, “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 the 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’s stomach according to each day after birth, sometimes compared with fruit or different-sized marbles and balls. A mother sent this picture to us which was in her hospital room after the birth of her baby. She also received inaccurate information and thought her formula fed baby only needed 5 ml at each feeding. 

I continued to search for more resources and I found more recent research in 2013 from  Nils J. 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 (1)

I also found this research depicting infant stomach size.StomachSize

According to Dr. Bergman, “There is a reasonable consensus on the amount of milk that human term newborn infants need per day, figures given vary from 150 to 160 mL/kg/day.” This means that an average 3 kg or 6.6 lb newborn requires 450-480 mL or 16 ounces of milk a day.  At 66 Calories/dL, this would roughly be 100-106 Cal/kg/day, which is the published daily caloric requirement for a newborn.  This total volume can be given in smaller volumes more frequently or larger volumes less frequently, 2 ounces every 3 hours or 1.3 ounces every 2 hours.

His article poses the hypothesis that the feeding interval should be 20 mL every 1 hour assuming that the stomach empties only once every hour.

However, the real-life clinical application of this feeding interval would quickly lead to maternal and newborn exhaustion from lack of sleep and increased risk of postnatal depression, breastfeeding cessation, and even suffocation from a mother falling asleep with her newborn during breastfeeding. In addition, his feeding interval does not take into account that the stomach actually empties during feeding and therefore the feeding capacity of a newborn is higher than 20 mL. Feeding capacity and satisfaction actually depend on the release of the hormones CCK and amylin, which slow down stomach emptying and signals the brain to stop accepting food.

The clinical experience of health professionals has shown that even one-day-old newborns are able to comfortably tolerate 15-30 mLs per feeding. 30-60 mL every 2-3 hours would, in fact, meet a newborn’s full daily caloric requirement and therefore prevent starvation-related complications.

Here is another resource in the Pediatric Surgery Journal describing the newborn stomach anatomy, including the size of 30 ml at birth:

My concern as a long-time NICU nurse and IBCLC has always been why are mothers taught that their exclusively breastfed newborn baby’s stomach capacity is only 5-7 mL on day one. Gastric emptying is a continuous movement into the small intestine which allows for milk volume to be more than 5-7 ml every 2-3 hours as recommended.  The stomach is a muscular and expandable organ and its biological function is to hold food and fluids before entering the duodenum. Yes, some exclusively breastfed babies are in a state of fasting after birth from limited amounts of colostrum some mothers make. But some of these babies will develop complications from insufficient intake because parents are not taught how to identify the signs in order to prevent them.

But, as professionals we need to update our educational resources and identify the babies who may need timely supplementation before the onset of copious milk production. For mothers who desire to exclusively breastfed, donor milk must be made available for them to use if supplementation is needed. In order for babies to receive the full benefits of breastfeeding, they need to be safely fed at every feeding.

So how often should exclusively breastfed babies nurse?

There is no single right answer to this question because each baby has a different weight and unique caloric requirement. By just weight alone, a 6.6-pound baby has an average size stomach of 20 mL on day 1 and would require 40 mL or 1.3 oz of breast milk or formula every 2 hours to meet their basic metabolic needs or 60 mL every 3 hours. But babies should also be fed by infant cues to satisfaction. 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 the breast while exclusively breastfeeding. If a medical evaluation is not immediately available, especially before the milk has come in and/or while the baby is losing weight, supplementation may be needed before medical evaluation is available in order to prevent serious complications of insufficient feeding.

As you can see, It’s time to ditch the belly models and update our breastfeeding education resources.  Our babies are counting on us to keep them well-fed, meeting their metabolic needs with sufficient milk, and using the best and most current infant feeding practices possible.

See below for additional resources:

Pediatric Anatomy Surgery Journal

Normal third-trimester fetal anatomy -ultrasound videos: the abdomen:

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

Breastfeeding confidence and measurement of milk intake

The American Academy of Pediatrics’ Breastfeeding Guidelines

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

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

Normal Human Lactation; closing the gap

Based on this literature review, for the purposes of analysis, we safely defined an overfed meal as any feed greater than or equal to 30 mL on DOL1.


National Women’s Health Advocate Describes How A Baby-Friendly Hospital Starved Her Baby

Two Physicians Describe How Their Baby-Friendly Hospital Put Their Newborn in Danger

We Were Awarded A Malpractice Financial Settlement Because My Baby Suffered From Starvation In A BFHI Hospital

NICU Nurse Discloses Newborn Admission Rates From Breastfeeding Complications in BFHI Unit

Nurses Are Speaking Out About The Dangers Of The Baby-Friendly Health Initiative

My Baby Starved at Kaiser Permanente – I Was Told Her Stomach Size Was Only 5 mL


Neonatal Nurse Practitioner Speaks Out About The Dangerous And Deadly Practices Of The BFHI


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18 thoughts on “The Newborn Stomach Size Myth: It’s not 5-7 mL

  1. Julie H says:

    I have been an NICU RN for more than 30 years… never have I seen a stomach in all the X-rays I have seen that only hold 2-5 cc…babies have been drinking amniotic fluid for 8 months…that is how they pee….so very glad to see you approaching this topic

  2. jane says:

    It seems to me that all of these studies fail to take into account what babies can and will take in naturally at the breast. Blowing up bellies with balloons until regurgitation is induced, ultrasounds and autopsies, don’t give a realtime assessment of what is normal. I recall a study done in Belarus showing average intake over the first 24 hours of breastfeeding was 37 ml and intake varied from 0-20 ml per feed. The fact is that hospital births and routines and policies are artificial environments and alter greatly what is normal and physiological. Perhaps using cherries as a visual representative of the size of a baby’s stomach is not accurate when compared to these artificially obtained volume studies, but it DOES accurately represent what some studies have shown to be normal intake at the breast.

    • Christie del Castillo-Hegyi MD says:

      Those studies showing that an average exclusively breastfed baby takes 37-60 mL the first day of life measured those values because that is the maximum a mom can produce on the first day. It means that mothers actually don’t produce the number of calories a newborn needs to feed all their living cells and not experience fasting physiology. That is the reason why breastfeeding mothers all over the world before the WHO used prelacteal feeding, either the milk of wet nurses, sugar water or animal to supplement their newborns the first day of life to prevent starvation. That is the reason why most exclusively breastfeed newly born babies are crying by the second night. Because they are in fact hungry, if not, starving. There is no evidence the giving birth in a hospital or artificial “interventions” are the sole causes of insufficient or delayed breast milk production. The majority of causes are physiologic stresses like blood loss the reduce milk production. Physiologic stress and low blood pressure prevent milk production because mothers would not have the fluid and caloric surplus to give up. One day old babies in clinical experience easily take 20-60 mL in one feeding because the feeding volume is not limited by the stomach size because it is not a blind pouch but a tube. The stomach empties during feeding into the small intestine and fullness is actually determined by the release of hormone signalling satisfaction. Furthermore, the stomach size does not actually change from day 1 to day 3 that quickly as well as feeding capacity. The small stomach theory is derived from the belief that a mother’s milk must be the exact amount a baby needs, which is not true.

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  4. Jocelyn Bootle says:

    I just wanted to verify that the individual who wrote this article is in fact an IBCLC? I was unable to find her in the registry?

  5. mitchsmom says:

    Regardless of stomach size, I would think we could all agree that we should follow what nature has modeled for eons.
    Maybe the stomach is larger than 5 or 10mL if filled to capacity, but maybe nature has a reason for not filling it.
    Adult stomachs can hold way more than we should eat.
    The human race generally thrived for thousands of years without measuring and arguing about stomach capacity, by what was available: breastfeeding & wet nursing.

    I believe it makes sense that we should model infant intake based on the physiological norm. And the physiological norm for humans is what normal, healthy breastfed infants take in.

    The goal is to have healthy babies, and this generally produces the healthiest babies.

    • Christie del Castillo-Hegyi MD says:

      The safe physiological norm is to meet the metabolic requirements of a newborn infant, which accord to the WHO is 100-110 kcal/kg/day, the amount required to prevent starvation. That equals 5.5 oz/kg/day or 2.5 oz/lb/day of breast milk or formula. Forcing an infant to endure days of underfeeding, letting them cry it out to maintain exclusivity can result in starvation-related complications like hypoglycemia, dehydration, hyperbilirubinemia and hypernatremia. Furthermore, the feeding capacity is not limited to the fixed stomach volume because the stomach empties during a feeding in response to internal signals of hunger and satisfaction which promotes peristalsis when the infant is hungry and slows when the infant is full. Therefore, newborn infants whose mother’s milk comes in by day 1 or 2 can and do feed on their full requirement, which is about 60 ml every 3 hours. Western exclusive breastfeeding advocates have a misguided obsession with exclusivity, biological purity and avoidance of supplementation that have saved millions of babies from starving when breast milk is not enough. That is why we shed light on the lies parents are being fed by such advocates the force their babies into hospitals and cause brain injuries that result in long term disabilities.

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