"It is often said that breast is best. But bottle-fed babies are the best behaved.Believe it or not, the study is actually really interesting - the media coverage as usual, is not.
A study of British infants found those who were breast-fed cried more, smiled and laughed less and were harder to soothe and get off to sleep than their formula-fed counterparts.
The Cambridge researchers however, say that the irritability linked to breastfeeding is only natural, and not a sign of stress or even necessarily hunger.
Instead, it is the baby’s way of bonding and seeking attention and security." (Daily Mail)
But lets get started!
Firstly it's a small study group of 316 infants, further divided into breastfed, mixed fed, formula fed - meaning there isn't a huge study group of each, still I think it's worth a read (1).
The study asked mothers of three-month-old babies to assess their "behaviour" (you can read more about exactly how here), which is what is really the interesting bit in studies such as these. It's subjective - how a parent "rates" their baby is open to many influencing factors.
As the NHS points out the study doesn't take into account:
- factors that influenced the choice of feeding method
- whether the mother worked
- other children in the home
- mother’s educational achievement and their perception of infant temperament
But to be fair, the authors do acknowledge this in the paper:
"Findings from such observational studies do not provide evidence for causality."They also acknowledge that studies in this area are contradictory, But what the heck, let's run with it and suppose its correct!
Something the NHS doesn't mention, and which I think is worth noting - is a study from The Journal of Child Psychology and Psychiatry, April 2011 which found:
"Mothers who feed their babies breast milk exclusively, as opposed to formula, are more likely to bond emotionally with their child during the first few months after delivery. "The breastfeeding mothers surveyed for the study showed greater responses to their infant's cry in brain regions related to caregiving behavior and empathy than mothers who relied upon formula as the baby's main food source."
As it's these same mothers who are then asked to rate their baby's crying - one would, based on the above expect non breastfeeding mothers to note a lower score perhaps?
If you're asked to rate something on a scale - we have to have a frame of reference for this measurement, something with which to compare. If you were an alien and had never seen a baby before, had no preconceived ideas about how much babies were meant to cry and were alone somewhere with no one to ask, how could you begin to rate whether crying was 2 or 7?
A scale such as this relies up an automatic, subconscious frame of reference - which may become conscious ie how much does my baby cry compared to X, Y and Z's. For many breastfeeding mothers, given breastfeeders are the minority - this comparison takes place with non breastfed infants; which, if this study is correct is likely to be significant..
Now we know breastfeeding is the biological norm, the milk humans are meant to consume - therefore it's pretty safe to say they cry a "normal" amount of time. The assumption it's "well behaved" not to, according to this study is flawed. It states:
So crying isn't just about stress, but about signalling - particularly with regard to hunger. Hmmm so if those not breastfed veer from this normal signalling pattern, is that a good thing?"Humans often perceive infant crying as stress, but for infant animals irritability is a normal component of signalling to parents. The expression of offspring demand is part of a dynamic signalling system between parents and offspring, and has received much attention from zoologists studying a variety of bird and mammal species."
One argument that has been put forward is that non breastfed babies cry less because they need feeding less frequently (given foreign milk protein is harder to digest and therefore takes longer).
Others like co-author of the study Dr Ken Ong feel:
However - what's really quite interesting is some little known research by Philip Zeskind, an associate professor of psychology:
“Bottle-fed babies may appear more content, but research suggests that these infants may be over-nourished and gain weight too quickly. Our findings are essentially similar to other stages of life; people often find that eating is comforting.”Perhaps this is true...
However - what's really quite interesting is some little known research by Philip Zeskind, an associate professor of psychology:
"Bottle-fed babies in some ways resemble an out-of-tune automobile, while breast-fed babies appear to be more alert, perhaps because their bodies simply run better, a Virginia Tech study shows.
Breast-fed babies develop a more energy-efficient and rhythmically functioning autonomic nervous system, which controls infant arousal, than bottle-fed babies, says Philip Zeskind, associate professor of psychology, who studied the sleep-wake patterns and heart rates of breast-fed and bottle-fed newborn infants.
"Although breast-fed babies are perceived to be more irritable than bottle-fed newborns,"Zeskind says, "our results suggest that the behaviors of breast-fed infants are physiologically more desirable. Feeding infants formula may make them sleep more and may disrupt the smooth running of their arousal systems."
Zeskind looked at babies in all stages of behaviour: deep sleep, dream sleep, drowsy, alert, fussing, and crying. Bottle-fed babies were found more often in the deep-sleep state, and breast-fed babies were more alert. Breast-fed babies also had lower heart rates, indicating better energy efficiency. "This argues against the idea that breast-fed babies are just more aroused and hungry,"Zeskind says. "If they were, they'd have a higher heart rate."
Computer analyses also show that the heart-rate patterns of breast-fed babies are more rhythmically complex, another indication of a more energy-efficient system. Basically, bottle-fed babies are like an automobile engine out of tune, Zeskind says. A less smooth-running arousal system has to work harder and use more fuel.
Which neatly all ties back in with the SIDS research and disruption of the arousal system..
But heck, what does it matter if not breastfeeding can have a notable impact on infant mortality, even in a rich country like America - so long as the baby is "well behaved" right?
Those breastfed and those not may indeed cry different amounts, may be perceived as more irritable or fussy - but this is the human norm. Ultimately beyond parental convenience, there really doesn't seem to be much evidence to support that it's healthy for baby to veer from normal signalling patterns - nor much known about the longer term, potentially lifelong impact.
The study concludes: Increased awareness of the behavioural dynamics of breastfeeding, a better expectation of normal infant temperament and support to cope with difficult infant temperament could potentially help to promote successful breastfeeding.
Those breastfed and those not may indeed cry different amounts, may be perceived as more irritable or fussy - but this is the human norm. Ultimately beyond parental convenience, there really doesn't seem to be much evidence to support that it's healthy for baby to veer from normal signalling patterns - nor much known about the longer term, potentially lifelong impact.
The study concludes: Increased awareness of the behavioural dynamics of breastfeeding, a better expectation of normal infant temperament and support to cope with difficult infant temperament could potentially help to promote successful breastfeeding.
PS, Funding:
"The Cambridge Baby Growth Study was supported by the European Union, the World Cancer Research Foundation International, the Medical Research Council, the Mothercare Charitable Foundation and the NIHR Cambridge Biomedical Research Centre. BL was a recipient for a grant from the ``Societe Francaise de Nutrition''. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist."
1. Breastfeeding and Infant Temperament at Age Three Months, de Lauzon-Guillain B , Wijndaele K , Clark M , Acerini CL , Hughes IA , et al. 2012 Breastfeeding and Infant Temperament at Age Three Months. PLoS ONE 7(1): e29326. doi:10.1371/journal.pone.0029326
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