Formula Use & Breastfeeding: The Moral of the Story

Earlier this week a study appeared in Pediatrics that has the media buzzing about whether giving formula in the first few days can actually improve breastfeeding rates. Both Time magazine and the New York Times featured stories on this. Not surprisingly, the media stories (and in my opinion, the researchers themselves) missed the central point.

This study compared breastfeeding outcomes in two groups of mothers whose babies had lost enough weight shortly after birth to be considered at risk. Both groups were given lactation help. In the control group, the mothers were encouraged to exclusively breastfeed. In the intervention group, after each breastfeeding the mothers were instructed to feed their babies by syringe a tiny amount of formula supplement: 10 mL, or about one-third of an ounce. This is about how much colostrum babies consume at each breastfeeding during the first 2 days of life.

The study found that more of the mothers who gave this small amount of formula after feedings breastfed longer and more exclusively than the mothers who didn’t.

Unlike the authors and the media, I don’t interpret these results to mean that early formula can help breastfeeding. In addition to all of the valid points made by other breastfeeding supporters, what was noteworthy to me was that the mothers in the intervention group were taught to supplement their newborns with biologically appropriate feeding volumes consistent with the recommendations of the Academy of Breastfeeding Medicine.

Many parents who supplement—including I’m sure those in this study’s control group—overfeed their babies incredibly, either without realizing it or because they are unwittingly instructed to do so by health professionals. Yesterday I spoke to a mother who was told by a pediatrician to make sure her jaundiced 4-day-old took 2 oz. (60 mL) at every feeding, which is twice the size of a 4-day-old’s stomach. To accomplish this, she was pumping, adding formula to her milk, and force-feeding this massive amount to her newborn.

My take-away message from this study is that any mother who supplements her newborn (whether with expressed milk, donor milk, or formula) should learn the appropriate amount to feed so she can prevent the kind of rampant oversupplementation that undermines breastfeeding and increases later risk of obesity. Babies overfed at this magnitude breastfeed much less often and milk production suffers.

What are the long-term effects of early overfeeding? One study followed to adulthood 653 people who were formula-fed from birth. Amazingly, greater weight gain during the first 8 days of life was associated with increased incidence of overweight 20 to 30 years later.  These researchers concluded that the first 8 days may be a “critical period” during which human physiology is programmed.  This may mean that breastfed babies’ greater weight loss after birth and slower return to birth weight may help promote a healthier metabolic program, which reduces the risk of overweight and obesity during childhood and beyond. At the very least, it most certainly means that parents and health professionals should be extremely wary of overfeeding newborns. To me, that’s the real moral of the story.

References

Academy of Breastfeeding Medicine.  ABM clinical protocol #3: Hospital guidelines for the use of supplementary feedings in the healthy term breastfed neonate.Breastfeed Med 2009; 4(3): 175-82

Bakalar, N. How formula can complement breastfeeding.New York Times, May 13, 2013.

Flaherman, V.J., Aby, J., Burgos, A.E., Lee, K.A., Cabana, M.D., & Newman, T. Effect of early limited formula on duration and exclusivity of breastfeeding in at-risk infants: An RCT.Pediatrics 2013; 131(6):1059-65.

Naveed, M. et al.    An autopsy study of relationship between perinatal stomach capacity and birth weight. Indian J Gastroentero 1992;11(4):156-58.

Rochman, B. How formula could increase breastfeeding rates.Time, May 13, 2012.

Stettler, N. et al.  Weight gain in the first week of life and overweight in adulthood.Circulation 2005; 111:1897-1903.

Stuebe, A. Early, limited data for early, limited formula use. Academy of Breastfeeding blog. May 13, 2012

Newborn Weight Loss and IV Fluids in Labor

Until now, weight loss during the first 3 to 4 days after birth has been considered one indicator of how early breastfeeding is going.  If on Day 4 a newborn’s weight loss is in the average range of 5% to 7%, this usually means breastfeeding is going well.   Nearly all babies lose some weight after birth.  Normal weight loss comes from the shedding of primarily body fat, which leaves babies well hydrated as they adjust to life on the drier outside. 

But when babies lose more than 7% of birth weight during these early days, does this automatically mean they are not getting enough milk?  No, according to a recent study. 

A greater weight loss may be completely unrelated to breastfeeding and due instead to excess IV fluids mothers receive within the final 2 hours before delivery.  According to this STUDY, these excess IV fluids inflate babies’ birth weight in utero and act as a diuretic after birth.  Babies whose mothers received more IV fluids before birth urinated more during their first 24 hours and as a result lost more weight.  Number of wet diapers during the first 24 hours predicted infant weight loss.  This was true whether the babies were born vaginally or by c-section.  Another study published earlier this year had similar findings.

This weight loss has nothing whatsoever to do with breastfeeding and milk intake.  In fact, the authors suggest that if clinicians want to use weight loss as a gauge of milk intake, they calculate baby’s weight loss not from birth weight, but from their weight at 24 hours.  According to their findings, this could neutralize the effect of the mother’s IV fluids on newborn weight loss.

This is one more reason weight loss alone should not be used to determine when newborns need formula supplements.   The Academy of Breastfeeding Medicine put this well in one of its 2017 PROTOCOLS: “Weight loss in the range of 8-10% may be within normal limits….If all else is going well and the physical exam is normal, it is an indication for careful assessment and possible breastfeeding assistance.”

Should All Breastfed Babies Have Above Average Weight Gains?

Just like in the fictional Minnesota town of Lake Wobegon, where “all the children are above average,” many parents believe there is something wrong if their breastfeeding baby’s weight isn’t above the 50th percentile.  While it is human to want our children to excel, the assumption that babies at a higher weight percentile are healthier or somehow “better” reflects a basic misunderstanding of growth charts and what they mean.

The purpose of a growth chart is to plot a baby’s growth on a series of percentiles, with the average baby at the 50th percentile.   What this really means in terms of weight is that out of 100 children, 49 will weigh less and 50 will weigh more. A weight that falls at a higher percentile is not “good” and a weight that falls at a lower percentile is not “bad.” By definition, there will be healthy children at every percentile.  Some will be chunky and some will be petite, but their percentile does not necessarily reflect their overall health or growth. 

A child at the 5th percentile is not necessarily growing poorly and the child at the 95th percentile is not necessarily growing well.  That’s because growth can only be evaluated over time.  For example, a preterm baby born very small will likely fall on a low percentile for weight at first, even when he is gaining weight well.  Also, if during pregnancy a mother had high blood sugar levels, gained a lot of weight, or received lots of IV fluids during labor, her baby’s birth weight may be unnaturally high.  In these situations, after birth a large baby may fall in percentiles to a weight closer to what his genes naturally dictate.1

But parents are not the only ones confused.  A U.K. study2 examined both mothers’ and healthcare providers’ perceptions of growth charts, and found that many mothers worried about their baby’s weight gain between checkups and that both mothers and healthcare providers erroneously considered the 50th percentile a goal to be achieved.  When babies fell below the 50th percentile, healthcare providers often recommended the mothers give their babies formula and solid foods to try to boost baby’s weight gain to reach this “desirable” percentile.  The researchers concluded that healthcare providers need more training on how to assess the growth of breastfeeding babies and how to support breastfeeding rather than undermine it.

Normal growth means a baby is gaining weight at a healthy pace and growing well in length and head circumference.  One point on a baby’s growth chart should never be considered in isolation but rather compared to other points.  It’s a baby’s growth pattern over days, weeks, and months that provides an accurate picture of how breastfeeding is going.  If a baby is growing consistently and well, his actual percentile is irrelevant. 

If over time, however, his weight-for-age percentile drops, first it’s important to determine whether the chart is based on breastfeeding norms, as many are not.  (Click here for the World Health Organization’s growth charts based on exclusively breastfed babies.)  If the chart is based on breastfed babies and the baby’s weight-for-age percentile has dropped, this is a red flag to take a closer look and see if breastfeeding dynamics can be improved.  

References

1Mohrbacher, N.  Breastfeeding Answers Made Simple: A Guide for Helping Mothers.  Amarillo, TX: Hale Publishing, 2010.

2Sachs, M., Dykes, F., & Carter, B. Feeding by numbers: an ethnographic study of how breastfeeding women understand their babies' weight charts.Int Breastfeed J 2006; 1:29.