I do feel like I am beating a dead horse here with this paper but bare with me a little longer!
The last myth I want to talk about is the so-called myth that breastfeeding does not protect against obesity.
The authors of the paper Myths, Presumptions and Facts about Obesity in the New England Journal of Medicine make this argument based in part on assertions that the WHO data on breastfeeding is biased. They then go on to discuss a very large randomized control study of 13,889 Belarus children whose mothers received breastfeeding promotion and were then seen at intervals until 6.5 yrs of age. ( Probit Study)
They ascertain that there is no real difference between the control group and the breastfeeding promotion group when it comes to weight/obesity at 6.5 years of age.
So here is the problem with this study:
1) All the children were initially breastfed. All participants were breastfeeding mother- baby dyads.
2) At 3 months 6.4 percent of the babies in the control group were exclusively breastfed versus 43.3 percent in the promotion group.
At 6 months 0.6 percent of the control group babies were exclusively breastfed versus 7.9 percent in the promotion group. Which means at this point virtually all the babies were eating something other than breast milk. What quantity of breast milk were they receiving?
3)For any amount of breastfeeding, the numbers are as follows:
3 months: 60 percent breastfed in control group, 72.7 percent in promotion group
6 months 36.1 percent breastfed in control group, 49.8 percent in promotion group
9 months 24.4 percent in control group, 36.1 percent in promotion group
12 months 11.4 percent in control group, 19.7 percent in promotion group
A portion of the control group continued to be breastfed to some degree until 1 year of age!
4) The Pediatrics paper (which the NEJM group quote), based on the Probit data was looking at behavioural outcomes including conduct disorder, peer interactions, hyperactivity and so on. The authors of this paper conclude that long-term behavioural outcomes of breastfeeding can’t be extrapolated from this paper as all the children were initially breastfed. It was not a true indication of formula feeding versus breastfeeding.
How much breastfeeding is enough? If, by 6 months, 99 percent of the control group and 92 percent of the promotion group were eating something else, perhaps this might affect your obesity outcomes? Or, perhaps, if by 6 months, one-third of your control group is still receiving some breast milk , this might affect your obesity outcomes? Or maybe if at 6 months, half your breastfeeding group has stopped breastfeeding, this too might affect your outcomes? Were these variables controlled for?
Is breastfeeding, once it is no longer “exclusive”, defined as once per day, ten times per day?
When is breastfeeding protective? Maybe those first “exclusive” days and months that both control and treatment groups were exposed to, is the critical timeframe?
The Belarus study was a fairly homogenous population, ethnically. What about the babies from different ethnic backgrounds, in a diverse population? Genes aren’t the only factor to consider, but they are important.
In the first year, it is known that the weight gain trajectory slows for breastfeeding babies.
We know that in breastfed babies:
Allergy related illness and certain infections are also less.
Moms also tend to have an easier time reducing pregnancy weight gain if they breastfeed.
I am not convinced that this is a myth. In my clinical experience, seeing hundreds and hundreds of children for obesity management, the breastfed guys are more aware of satiety cues. They seem to regulate the amount that they eat in a different way.
What do you think?
My thanks to Dr. S Gross- breastfeeding expert, for her insight, which made me dig deeper.