The benefits of breastfeeding to a young infant’s health are well-documented (though sometimes debated), and the American Academy of Pediatrics (AAP) recommends that babies be breastfed for the first year of life if possible. Are there any health benefits to the child for breastfeeding beyond a year? I am curious about this as my daughter approaches her first birthday.I shouldn’t have been surprised to find that there have been very few studies of extended breastfeeding (> 1 year) conducted in the developed world. Breastfeeding research is notoriously hard to do, and good research on extended breastfeeding is nearly impossible. As a population, women in the developed world who breastfeed their babies are already likely to be different from mothers who choose not to breastfeed, setting their babies up for different outcomes well before their boobs even hit the baby’s lips. (This is of course a very broad generalization, and I recognize there are exceptions.) These differences are likely even greater in women who choose to breastfeed beyond a year. Only 24% breastfeed to one year in the U.S. , and we don’t know how many continue beyond that. These mothers are more likely to be well-educated, white, older, richer, buying organic food, fretting about BPA exposure, and the list goes on. Sure, we can use statistics to try to account for these confounding variables, but these methods require (A) that you’ve identified the most important variables, and (B) that you have study participants that represent a spectrum along that variable. This research is hard to do.
It is also important to point out that breastfeeding research conducted in developing countries does not tell us anything about outcomes in the U.S. and other developed countries. There is real evidence that extended breastfeeding benefits children in the developing world, where young children are challenged by malnutrition and greater exposure to infectious diseases, which is why the World Health Organization recommends breastfeeding for two years. My child has access to balanced nutrition and clean water, so whether she nurses beyond a year is less likely to affect her health.
These caveats aside, is there any research to support extended breastfeeding for the sake of my child’s health?
The AAP policy statement on breastfeeding doesn’t discuss breastfeeding beyond a year so didn’t provide any leads. Next, I checked the policy of the American Academy of Family Physicians (AAFP). On nursing beyond infancy, the AAFP position paper states,
“As recommended by the WHO, breastfeeding should ideally continue beyond infancy… It has been estimated that a natural weaning age for humans is between two and seven years . Family physicians should be knowledgeable regarding the ongoing benefits to the child of extended breastfeeding, including continued immune protection , better social adjustment , and having a sustainable food source in times of emergency.” And on weaning a child due to a subsequent pregnancy, they state: “If the child is younger than two years, the child is at increased risk of illness if weaned [no citation].”
Let’s look at the research cited by the AAFP:
Should I wean my child at the “natural age”?
Katherine Dettwyler is an anthropologist at the University of Delaware. The reference of her work in the AAFP statement is for a book chapter that she wrote , but you can also read a summary of her research on her personal webpage. Dettwyler reviewed research on weaning in non-human primates and extrapolated from those observations to determine that the “natural” age of weaning of humans should be 2.5-7 years.
While I appreciate this anthropological perspective, I think it is inappropriate for the AAFP to make recommendations to humans based on what monkeys do. The monkeys do what they do because it probably does benefit their offspring, but this is not evidence that extended breastfeeding will benefit my child. And early human societies probably did breastfeed their children beyond a year. Let’s say that you were a mother raising a baby in a hunter-gatherer society. In your world, you don’t have a safe way to store food, so you have periods of relative feast and relative famine. Your food supply on a given day depends on the success of the most recent hunt and the seasonal availability of wild plant foods. Babies and toddlers don’t cope well with intermittent food supply. They need to eat often to support their rapid rate of growth and development. Of course you would breastfeed as long as possible so that you could provide your child with a reliable source of nutrients. This would allow you, the mother, to store calories and nutrients when food was abundant and later mobilize them to breast milk so that your child could continue to eat even when food was scarce. This is a brilliant evolutionary advantage of mammalian lactation, but it doesn’t really apply in today’s developed societies, where most children have ready access to more than enough calories and nutrients.
Does extended breastfeeding give my child immune protection?
The AAFP cites a 1983 study , which shows that concentrations of IgA, lactoferrin, and lysozyme are similar between 12 and 24 months of lactation. However, this was a tiny cross-sectional study, involving just 15 milk samples. And though it tells us is that breast milk still has immunological proteins in the second year of breastfeeding – we don’t know if breastfed toddlers are actually less likely to get sick.
Will my child have better social adjustment if I breastfeed longer?
To support their statement that extended breastfeeding leads to better social adjustment, the AAFP cites a prospective study of 1024 New Zealand kids enrolled at birth and studied for 8 years . The study looked at correlations between duration of breastfeeding and conduct disorders, which were assessed by both the children’s teachers and their mothers. Once the data were adjusted for confounding variables such as family income or disruptions such as divorce, there was a small but significant correlation between longer breastfeeding and better conduct scores, as assessed by the mothers. In other words, the mothers that breastfed their children longer thought a bit more highly of their children, but mothers can be sort of biased, don’t you think? There was little relationship between breastfeeding and the teachers’ scores. The authors conclude, “Certainly, the results provide no support for the view that prolonged breastfeeding makes a major impact on subsequent social adjustment.” I agree – there are lots of ways to influence your child’s behavior in elementary school, but based on this study, breastfeeding is unlikely to help much.
Is breast milk a good food source in times of emergency?
Yes! I’m comfortable saying this even without any science to back it up. If we are ever victims of an earthquake or some other natural disaster, I can imagine it would be very useful to be lactating so that I know I have a ready-made clean source of food and water for my child. However, I probably won’t make my decision based on this unlikely event.
Is my child at increased risk for illness if weaned before 2 years?
Although the AAFP makes this statement, they don’t provide any research to back it up. I looked through countless other studies as well, and I couldn’t find anything to support this statement. So as far as we know, your child will be just fine if you wean before 2 years.
Needless to say, I’m disappointed in the AAFP. I whole-heartedly respect the mission of promoting breastfeeding and believe mothers should be supported if they want to continue breastfeeding beyond a year, but you shouldn’t have to stretch the truth about scientific studies to do so. Most women would read the AAFP’s policy statement and conclude that there is scientific evidence that their kids will be healthier and better-behaved if they breastfeed to two years. Women deserve to have accurate information with which to make their choices. You can tell them that they might enjoy breastfeeding their toddler and there is no rush to wean. You can even say that there may be health benefits, but there isn’t enough research to say for sure. Just don’t cite scientific evidence where there is none. Based on the research cited by the AAFP, there is no scientific evidence that it will compromise a child’s health to wean at a year.
I did read many more studies than these few cited by the AAFP, but this post has already gone on too long. I’ll let you know what data I did find and my own decision about breastfeeding beyond a year in uncoming posts. If anyone has run across a study that looked at breastfeeding beyond a year in the developed world, please pass it on!
What do you think? Does the end justify the means? Is it fair for the AAFP to stretch the scientific evidence to encourage women to breastfeed longer?
1. CDC, Breastfeeding Report Card – United States, 2011. 2011.
2. Dettwyler, K.A. A Time to Wean, in Breastfeeding: Biocultural Perspectives, D.K. Stuart-Macadam P, Editor. 1995, Aldine De Gruyter: New York, NY. p. 39-73.
3. Goldman, A.S., R.M. Goldblum, and C. Garza. Immunologic components in human milk during the second year of lactation. Acta Paediatr Scand. 72(3): p. 461-2. 1983.
4. Fergusson, D.M., L.J. Horwood, and F.T. Shannon. Breastfeeding and subsequent social adjustment in six- to eight-year-old children. J Child Psychol Psychiatry. 28(3): p. 379-86. 1987.