Dear all:

I spent all yesterday working on my response to one of the authors and a reviewer of the article featured in "The Joy of Feeding, Without All the Parental Angst"  http://www.nytimes.com/2011/12/13/health/views/the-joy-of-feeding-without-all-the-parental-angst.html?emc=tnt&tntemail1=y which is based on the PILOT STUDY "Preventing Obesity During Infancy: A Pilot Study "http://www.nature.com/oby/journal/v19/n2/full/oby2010182a.html

In fact I was so distracted that a colleague and I were completely sidetracked by this issue when we were supposed to be meeting about finalizing the books on an excellent workshop that Kay Hoover did for interns. We were so distracted about this issue that we forgot to pay the check at the cafe where we had lunch.  Fortunately, the staff were relaxed about it when my colleague went back to pay the bill.  Apparently Ben Stiller had done the same thing the day before.

So.... first I complemented them on responsive feeding, then I went through the potential problems.  This is a shortened version since all of you know the varied different patterns of infant feeding -- I'm using shorthand

Problem 1: Relationship between Sleep and Obesity
The findings of “Short Sleep Duration in Infancy and Risk of Childhood Overweight” by Elsie M. Taveras, MD et al in the Arch Pediatr Adolesc Med. 2008 seems to have been used to justify sleep training as a means of preventing obesity.  http://archpedi.ama-assn.org/cgi/content/full/162/4/305

Concern A:  Self-reported Sleep
Taveras' sleep study used self-reported sleep.  James McKenna has documented how parents are an unreliable source on how long their infants actually sleep.  In fact recent studies using wrist monitors have blown the myth that formula fed babies sleep longer out of the water as evidence in "Breast-feeding duration increases sleep duration of new parents" by Doan et al, Journal of Perinatal and Neonatal Nursing, 2006 July/September; 21(2):200-206.  

Concern B: Potential Reverse Causality
I have noticed that babies who regurgitate often have difficulty sleeping. These babies typically gain at a rate of 2 oz/day and don’t slow down until their digestion settles down --- or mothers learn to distinguish between pseudo hunger cues and actual hunger cues.  The problem may not be the lack of sleep causing obesity; it may that the discomfort from indigestion causes babies to overeat or parents to assume they are hungry and the resulting overeating causes them to eat more than they should.  

Concern C:  Extrapolation beyond the evidence  
The findings of Taveras’ study is an association with the average duration of sleep at 6 months, 1 year and 2 years and overweight at three years were cited in the rationale for sleep training.  The other studies cited in her paper deal with sleep at even older ages. In many developing areas of the world, infants continue nighttime feedings well into the second year of life with no adverse increase in obesity.  Since Taveras’ study averaged the sleep duration over the entire period, we don’t know how sleep at six months relates to sleep at 1 year or at 2 years of age. 
 
Dr. Tavera’s study did not look at sleep at 2-3 weeks of age, nor the impact of withholding feedings from infants of only 2-3 weeks of age on their long term sleep and health.  Infants of 2-3 weeks of age have a stomach capacity of only 60-80 ml, need to feed 8-12 times per 24 hours, and full milk supply is not established until 5-6 weeks of age.   It seems precipitous to assume that one can apply research from infants who are neurologically more developed, are capable of eating solids, and when the mother’s milk supply has been firmly established to a much earlier developmental phase when sleep patterns, eating patterns and the mothers establishment of the milk supply are extremely different. 


Problem #2:  Appropriateness of the Intervention

Concern A:  Appropriateness of the Soothing Tactics for Regurgitators
Since I don’t have access to the full article, I do not know what tactics were being used to soothe babies in this pilot study.  If the problem is the regurgitation interfering with sleep, the soothing strategies need to correspond to reducing regurgitation, not just forcing the baby to sleep longer when the baby is really uncomfortable.  Since these babies are stressed already, forcing them to sleep on a flat surface may merely increase their cortisol levels even higher.  Since elevated cortisol levels are also a risk factor for obesity, inappropriate soothing strategies may backfire.  If appropriate soothing strategies are used to alleviate their discomfort, this may be the one group for whom soothing rather than feeding may work well.
 
Concern B:  Negative Impact on a Subset of the Study Population Masked in Aggregated Data
          
Self-Limiting Feeders:
There is also a different subset of the babies I see that are also regurgitators.  These babies will typically stop and scream when they have consumed at a set amount, well under the average intake for a feed.  The more severe cases typically end up being diagnosed with gastroesophageal reflux disease by their pediatricians.  These infants usually gain at ½ oz a day or less and consequently are usually failure to thrive. If their feedings are held off or if they are forced to drink larger amounts they can develop severely negative reactions to feeding, refusing the breast and bottle, extreme vomiting and/or severe growth restriction.

 
Problem 3:  Stunting was not evaluated as a potential outcome

My doctoral dissertation showed that the most significant and substantial response in linear growth was from 3-6 months and this period of linear growth was significantly associated with attained length at 2 years of age.  Give that my results show a potential long-term impact from slow length gain leading to permanent stunting by 24 months, I do feel that the three to six month interval deserves particular attention in any study that deals with infant feeding patterns.  Moreover, I am now finding that this interval is hugely problematic for many mothers in terms of the changes in infant behavior and worries about growth.  I have begun documenting the weight and often the length of infants during this interval and the common problems that drive mothers to have concerns.  

A)   Babies being overfed when:

1) health care practitioners use the old CDC curves and suggested supplementation with formula or premature introduction of solids for an infant who was actually growing normally on the WHO growth curve
2) mothers misread the age-appropriate development of very efficient quick breastfeeds and social distraction and incorrectly assume that the baby isn’t eating enough. 

	The responsive feeding strategies suggested in this pilot study may be helpful for these types of infants

 B)      Babies being underfed when:

1) babies whose rate of growth is initially borderline and then decelerates even further when they are encouraged to sleep a little longer and feed less frequently

2) health care practitioners aggressively pressure mothers to sleep train their babies to 12 hours of sleep starting at 6 weeks of age (a major pediatric group in the New York Metropolitan has steadily major pediatric group has steadily increased the severity of their sleep training methods and I’ve been seeing a direct link with increased failure to thrive and stunting in their practice - to a degree comparable to what I have seen in my many years of work in developing areas of the world)


3) mothers only allow the baby to feed from one breast at a feeding because they were told about foremilk-hindmilk imbalance, when they have babies who are incapable draining a single breast sufficiently to meet their needs or the milk storage capacity of the mothers’ breasts are inadequate to handle longer stretches without drainage

4) mothers with borderline glandular tissue that can maintain marginal growth initially, but cannot sustain that growth as the babies needs increase

These babies typically gain at a slower rate and even slow in linear growth.  If mothers do not receive appropriate counseling, they then overcompensate with the end result that their babies end up stunted and overweight.

Problem 3:  High Drop Out Rates
            My suspicion with the high drop out rates mentioned in the editorial (http://www.nature.com/oby/journal/v19/n7/full/oby2010235a.html) is that the parents who are most likely to continue to participate are those with babies who are regurgitators who eat large amount frequently and babies whose health care practitioners assumed they were not growing well enough because they were using the old CDC charts for weight gain.  There may be a subset of infants who did fail to thrive because of premature or overly aggressive “soothing” and whose parents ordinarily would have responded to the hunger cues with later overfeeding but did not because the study focused on soothing tactics and responsive feeding.  Since appetite suppression is common in failure to thrive, these infants may never have cued appropriately in relationship to their inherent genetic potential for optimal growth.  Since the data are aggregated it is impossible to tell what proportion of the infants are really at a very low end of the weight for length percentile.  
 
	 I suspect that the parents who are more likely to drop out are parents whose very young babies cannot tolerate having their feedings stretched at such a young age, babies are failing to thrive to such an extent that it is visible, or regurgitators whose parents are simply too exhausted or uncomfortable with their infants distress to attempt to soothe their babies rather than feeding them.  Parents who are uncomfortable soothing what appears to them to be a hungry baby will not want to continue the protocol.  If the babies that fail to thrive drop out and are not given the guidance to respond appropriately to their feeding cues, they may go on to be overfed.  In fact, this is what I have seen in my practice – initial low weight gain, accompanied by stunting, followed by overweight.  This is exactly the same pattern that is seen in exclusively formula fed infants and seems also to be seen when mothers bottle-feed breastmilk to their babies in ways that approximate formula feeding norms rather than the patterns of the breastfed babies which is the physiologic norm.  So, I would suspect that this pilot study might fail to capture both the rebound from failure to thrive to overweight as well as the escalating overfeeding of the regurgitating babies.


Best regards,

Susan E. Burger, MHS, PhD, IBCLC

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