Just 2 weeks ago, I won a machine learning contest with a $20,000 prize pool where the goal was to predict the IQ of a child at age 7, based on various biological measurements and demographic indicators. The data includes whether a child was breastfed.
After reading the article I did some very quick computations and my finding based on the model I developed is that children who were not breastfed have an IQ impairment in the 1-3 IQ points range, after accounting for confounding factors.
This is very consistent with the results published here.
Compared to this study, I believe the methodology I'm using is more powerful for three reasons:
- much larger sample size: the dataset I have access to comprises 12015 children, compared to 3493 for the study
- a larger set of confounding factors is accounted for: notably, the data includes height and weight measurements at up to five points in time
- confounding factors are fully accounted for, rather than hand-waved away. This is a complex model based on random forests and linear model, and the results are entirely cross-validated.
Stay tuned for more detailed computations. I will also ask the organizers for the exact definition of breastfeeding used.
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Edit:
On the other hand, the study is still very appealing because according to the authors, there is little correlation between demographics and breastfeeding in Brazil, whereas the validity of the effect I'm reporting is dependent on whether the demographic model is powerful enough to remove the correlation. Still, I believe most of the correlation is easy to remove, and it isn't clear that there aren't subtle demographic effects even in Brazil. In particular, the proportion of participants with missing IQ data seems to decrease with duration of breastfeeding, and I don't know if they have an explanation for that.
I compared my dataset and their data, and it turns out that even in Brazil there is significant correlation between mother education and breastfeeding, barely less so than on the dataset I have. So you should probably disregard my edit in the above post: accounting for confounders could be important in both cases.
Thank you for taking the time to comment about your work.
I came to comment on the headline, basically to say that "Breastfeeding 'linked to higher IQ'" sounds awfully backwards -- surely this isn't really a result "in favour of" breastfeeding, but rather pretty damning evidence against formulas/substitutes ?
I like your formulation much better:
> children who were not breastfed have an IQ impairment
I see the article climbing back up the front page, and I want to make it abundantly clear that I don't believe that there is necessarily a causal relation from breastfeeding vs formula to IQ.
I could control for demographic factors, but not for other major important factors in a child's development -- parental IQ or views regarding parenting are huge factors in a child's IQ, and they may also influence the decision of whether or not to breastfeed. If parenting books unanimously decided that formula was bad, then parents who cared enough about their children to read them and follow their advice would be more likely to breastfeed and you would see a positive correlation with IQ, even if formula was completely equivalent to breastfeeding.
So while there is a clear correlation after controlling for demographic, there is not necessarily a causation. My formulation really wasn't meant to imply causation, but rather the handling of unknown data (I grouped unknown-status children together with breastfed children). When talking about correlation, it's not meaningful to make a distinction between IQ impairment and IQ gain.
The contest was hosted on TopCoder. The name of the organization who provided the data and funded it is not public, but I'm told it will be made public at some point.
I've never gotten my IQ tested, but when I read about studies like these - they usually demoralize me from fear of competitive behavior. I think this leads to low self esteem, and the imagining that I have a low IQ (high marks through schooling and post graduate education, MSc, possible imposter syndrome) as my default attitude. It can be a self defeating attitude, but what it usually does is make me argue with people about IQ tests, and explain why they are not necessarily indicative of intelligence, individually or globally.
I can imagine that merely the act of measuring IQ has significant effect on the population. I can not imagine a population that exists without it, but I imagine it would also have a huge effect on society, as you similarly hypothesize about the 1-3 point increase across the population globally.
This, but also, IQ isn't an exact score, right? Wouldn't this fit snugly within the margin of error?
Not only that, but are people even still using IQ as a metric of intelligence? As I understand it IQ is only a measure of one type of intelligence. I mean I'm all for giving a child every advantage you can fathom as a parent, so I think this is still kind of cool research, but I don't see how it equates to anything truly meaningful.
It kind of just adds one more point in the "breastfeeding is good" column.
I found a big improvement to my model just after the contest was over, so I made a proposal to develop the improved model and do some more in-depth analysis. I'm currently waiting for their reply!
If they accept I'll have an opportunity to look deeper -- it's one thing to develop an efficient model, but fully exploiting it in order to gain a better understanding of the data takes some work. A limitation of these contests is that you're rewarded for producing a very efficient model, but there is very little emphasis on analysis of your model once you built it. I think it's a shame, because the person who built the model is often in the best position to have a good intuition of both the dataset and why the model had to be built that way.
I've been considering opening a blog, but I haven't found time to do so yet.
Briefly, the purpose of the contest wasn't to understand the effect of breastfeeding, but to understand how important normal child growth is to mental development. They included several scenarios: with all data available, with demographic data removed, and with demographic data and growth curves removed. Unfortunately, IQ is so overwhemingly affected by demographic that the scenarios without demographic data devolved into a game of extracting all the demographic data that was leaked by non-demographic variables. And when demographic data is available, more than 90% of the variance extracted by the model comes from demographic data rather than biological measurements!
It's really disheartening to think that depending on the social setting you come from, you start with an IQ of 85 or 115 -- at age 7...
I'm honestly totally in favor of breast-feeding, when it's a reasonable option. I don't want anyone to avoid breast-feeding because they think (as was believed for quite a while, actually) that formula is better.
But this line from the OP slightly freaked me out -- just for acknowledging the possibility:
> But they say mothers should still have a choice about whether or not to do it.
Have they forgotten the abortion debate? There are some relevant points in there, even if formula-feeding actually cost 50 IQ points, reliably.
But it's more than just that.
Parenting is demanding and unavoidably full of compromises, for just about all parents. Most people just think in overly-simplified terms of what's "right" and "wrong" in parenting decisions, which means that the mother who can't breastfeed because she's got mastitis gets to suffer both from the pain and from guilt of imagining her child's IQ points decreasing; nice.
But really -- feeling guilty whenever you see your child is probably quite a bit worse than any harm not breast-feeding them may or may not cause.
I feel like there should be just a list of priorities, for parents to review when they're choosing their individual compromises, and at the top of the list would be "dedicate time when you're feeling well to your child". Then you can spend that time actually being supportive, kind, fair, consistent, and all of those things that go out the window when you're feeling awful.
And you may be feeling awful if you're compromised away too much of your sleep, if you're in pain, if you've faked being happy for too long, because of some article you read about something that was "right" or "wrong" for your child.
All of these other things -- like breast-feeding -- should come below that.
Kids don't want/need more time, full-stop; they want/need more time with parents who are actually doing okay.
In some cases, the pressure to breastfeed can do more harm than good. If the parent is feeling stressed, as it can be an extremely intense and also painful experience, the bonding process can suffer. More importantly, some mothers just cannot produce enough milk. The father of my adopted son forced my wife to breastfeed. Over a 3 month period, the poor boy lost a dangerous amount of weight and needed a stay in hospital, where he had strict, formula-based feeding schedule. If my wife was asleep, the nurses wouldn't even bother waking her up, they'd just feed him.
The result, and not to say this is a cause but a potential contributing factor, is that this unfortunate boy has major developmental delays, is unable to speak properly and what he can say he often doesn't understand. I personally have had my past investigated by social services to ensure I won't have a negative impact on his development (I suffered from psychosis in my teenage years, likely due to stress from attention deficit disorder and a traumatic event). Teachers and myself have noticed, for example, he regularly speaks well out of context, which is notably worse than his peers. There's a tough road ahead.
With articles like this, we are looking at individual, specific factors when the reality is much more complicated and results from an interplay of thousands of microscopic to large and obvious factors. With children and their development, it is just not simple. We are, whether we like it or not, complex systems.
Parents of healthy body and mind want the best for their children. The pressure of this alone is fantastically great. The results of additional, external, pressure could do more harm than good.
The results of additional, external, pressure could do more harm than good.
Yup. My wife, for reasons no one could really explain, hardly produced any milk. Fortunately it only took us a few days or so to realize this and start bottle feeding, but a lot of the nurses and midwives we met along the way felt no compunction in making my wife feel like a failure as a mother and human being because of this.
Came here to write the same thing, my son was born 6 weeks early, hormonally my wife was not ready to breast feed at all, and we had a hugely painful, and for my wife embarrassing experience sitting hour after hour in the hospital with breast pumps and formula bottles trying to get enough, and the right balance of breast milk and formula into my son. The hospital were adamant that we kept at it, and now some four months in, I think my son has only had to be fed with ~20 bottles, total. Mostly when we're travelling or my wife and I are exhausted, I think it's a natural and important part of raising a child, but not everyone can do it, we were lucky, and we need more tolerance of personal choice or circumstance without being judgemental.
Of course until becoming a parent, I had my strong and largely invalid opinions (i.e breast feeding in public is inappropriate, etc) I'm happy to say I've got past those short sighted and ill conceived views and won't judge anyone for anything they do for their child, probably there's a damned good reason why they're doing it, lack of sleep, exhaustion, and a baby crying are pretty powerful motivators to step outside of one's own personal comfort zone.
Other hot topics (especially as a Brit living in Germany, seeing the cultural differences) are sharing a bed with an infant, bathing with them, skin-on-skin contact, etc, etc.
Yes, having a child changes you fundamentally. The difference in me has been dramatic. Despite all the stress, I am overall far more emotionally stable. I'm more industrious. There's no stress like having next to no sleep and having a screaming baby who needs you. Most things that work throw at you are nothing.
The most important thing is that it teaches you what is and isn't important in life, or at least it did for me. I used to panic when a server or website died at work. For me, now, it's nothing. Of course, it's still urgent and I fix but it actually gets done faster as I'm not stressing about it. The most important thing for me is having healthy and happy children. Work is now a means to that end.
I consider myself successful at this moment in time because my baby is happy, nothing else. Even doctors, whilst she was unwell, noted how happy she was. Her nursery notes how incredibly fast she is developmentally, both mentally and physically. That's all in spite of being bottle fed the majority of her life.
Skin on skin is beautiful. If you want to feel less stressed and find an unexpected inner peace, do skin-on-skin. It's known oxytocin is realised with skin contact, regardless. Doing so with your baby, knowing he or she is so totally dependent on you to live, makes for a profound experience.
+1000 Last night I got three hours of sleep, in one hour increments. Five month old has a cold and a head full of snot, would not sleep. My wife and I do night on, night off so one of gets some sleep every other night. I'm sitting at my desk wondering how I'm going to get my head into the code today. Three to four hours a night was common for the first 3-4 months.
About breast feeding, my wife produced plenty of milk, only the anatomy of her breasts keeps the baby from latching on. So she pumps and we bottle feed. She really wanted to breast feed this one, but it just didn't work out.
The most important thing is that it teaches you what is and isn't important in life, or at least it did for me. I used to panic when a server or website died at work. For me, now, it's nothing. Of course, it's still urgent and I fix but it actually gets done faster as I'm not stressing about it. The most important thing for me is having healthy and happy children. Work is now a means to that end.
I'm getting ready to propose to my girlfriend, and reading what you've written has made me immeasurably more excited to become a father. I constantly worry about what we're going to do when we raise our kids and if we'll raise well-developed, smart and productive kids, and this just gave me a shot of confidence that we'll do okay.
> but a lot of the nurses and midwives we met along the way felt no compunction in making my wife feel like a failure as a mother and human being because of this
That is absolutely horrible, sorry you had that experience.
My wife was in the same situation with our first, basically she anatomically did not have enough tissue to generate the volume of milk required.
Luckily we were able to get donor milk and rely on this technology: http://www.lact-aid.com/. Amazingly she was able to build enough tissue so that by our 3rd kid we have not used any donor milk at all.
Same experience. We noticed that things were not going well for our daughter, Maggie, too. I told her many times "Look, if you don't feel right about this, we can go on bottles". 6 days she endured, Maggie needing to be latched pretty much every minute. The midwives encouraged her to continue, despite clear signs recent history was repeating itself.
Regardless of anything else,6 days without sleep in any form is dangerous and encouraging that behaviour could really tear families apart. Even though it's disgraceful, with this type of pressure, it's no wonder we see shaken-baby syndrome.
It's been said that the NHS is wrongly focused on curative medicine as opposed to preventative medicine. If there was ever a case for it, I'm sure this would be one.
>> In some cases, the pressure to breastfeed can do more harm than good. If the parent is feeling stressed, as it can be an extremely intense and also painful experience, the bonding process can suffer. More importantly, some mothers just cannot produce enough milk.
This mirrors what happened to us in an NHS hospital in the UK. As a result, my daughter's blood sugar dropped dangerously low as we were encourage to persist in breast feeding for far longer than we should have.
She's also on the gifted and talented programme at her school now, so I don't think Formula did her any harm.
These issues are complicated to navigate for the midwives as well -- it's hard for them to know exactly who's hoping for more support, and who's really in need of an alternative option.
> More importantly, some mothers just cannot produce enough milk.
I'd guess this would be vanishingly rare, just due to evolutionary pressures over a long period of time, and there are other factors that just make nursing really difficult for many mothers. But I don't know for sure, and nowadays babies that would have simply died, or have killed the mother as well as died, can survive as a matter of course; so that changes the equation as well.
Breastfeeding (the first time around, especially) is quite a bit harder than most people realize -- it's partly a process of teaching the newborn what to do. They may be eager but default to a bad latch, they may be convinced their hand also needs to be in their mouth while they feed, or they may quickly pick up the habit of feeding for 20 seconds then taking a 2 minute nap, or they may decide they can only sleep while latched on. And those are just the problems we saw with our own two daughters!
But it is worth some serious effort (even if just for convenience, once it's working, among other benefits) -- it's just not worth destructive effort, and if it doesn't work out it's not worth remorse.
> She's also on the gifted and talented programme at her school now, so I don't think Formula did her any harm.
Right -- it's just so hard to predict. She might have been breastfed and yet be having difficulty in school as well; there are so very many factors involved, but many parents fix on a few (and torment themselves with guilt, or pride themselves on a choice well-made...).
But there are so many paths to a happy & healthy child who grows up to be a happy & healthy adult, and so many that go elsewhere, and many factors are totally out of our control.
"More importantly, some mothers just cannot produce enough milk" - Is there any anecdotal evidence to prove this. One lactation consultant told us that this claim is totally false. According to her, all women who give birth can and will produce enough breast milk and she had the evidence to prove that.
Honestly that opinion seems more colored by her political views (i.e. breast feeding good, formula evil) than any scientific or medical evidence.
I've met lactation consultants just like that, and they often go into diatribes about how hospitals/doctors are evil and push formula on new mothers (which wasn't true at all, in fact the hospital we used had a nurse specifically to help mothers breastfeed and offered heavily subsidised classes).
While getting started with breastfeeding is hard and mothers should be encouraged to keep at it. Some mothers simply never produce, even after trying that hard, or that long. At a point you're putting your child's life in danger if you keep trying without results (and, no, I do not mean after just a few hours -- that's normal, I mean days).
Honestly I'm pro breastfeeding but I find a lot of other pro breastfeeding people insufferable. No, sorry, but people are in fact good mothers or fathers if they use formula. No, sorry, they aren't automatically ignorant if they use formula. No, sorry, you or your child aren't superior because you breastfeed. No, sorry, it really isn't appropriate to approach random people in the street and lecture them on why they're raising their child wrong.
According to her, all women who give birth can and will produce enough breast milk and she had the evidence to prove that.
Bullshit (not you; her). The only way to prove that, given that humans are messy biologicals and not a mathematical equation, is to line up every woman who ever gave birth and demonstrate that each of them produces enough milk to feed said child. A single counter-example (of which there are many) demonstrates that she's talking rot.
Surely some mothers cannot produce enough milk, but this is the rallying cry justifying reverting to formula, much as "the baby was too big" is the rationalization for cesarean delivery. Surely it is true in some very small percentage of cases, but it cannot explain away the measured variations and choosing the sub-optimal path. Everyone has their own anecdote, but they can't all be biologically incapable of breastfeeding.
"Concern about insufficient milk supply is another frequently cited reason for early weaning of the infant.90,113–116 One national study on feeding practices found that about 50 percent of mothers cited insufficient milk supply as their reason for stopping breastfeeding.112 Having a poor milk supply can result from infrequent feeding or poor breastfeeding techniques,115,117–119 but lack of confidence in breastfeeding or not understanding the normal physiology of lactation can lead to the perception of an insufficient milk supply when in fact the quantity is enough to nurture the baby.120,121"
My wife's mother was unable to leave hospital until my wife put on weight. My adopted son lost tonnes of weight and only gained after bottle feeding. My daughter simply could not be taken away from the breast.
That was enough for me to make a decision that breastfeeding my second daughter was impractical.
EDIT: I do say "produce" but it may not be as simple as that, again it's complicated. Production may not be impaired, but perhaps the ability to dispense might be. There may be some matrilineal genetic factor present that prevents a baby from latching properly or taking enough milk. I'm not an expert but there are a few stages in the process where things can and do go wrong.
This is precisely what the lactation consultant said. So, my wife couldn't breast feed for the first couple of months and we assumed that she couldn't produce enough milk. We went to this consultant and all she did was to change the feeding position by a small degree. After that our daughter fed happily. The problem was not with production but with the latching technique and I wouldn't be surprised if this is the case with many women.
I do have a bias against bottle feeding because of our personal experience stated above.
I would love to see that evidence, since I have plenty of anecdotal evidence that it is bullshit.
And what's even worse, all the people pushing this nonsense do a lot of damage to all the women who cannot produce enough milk, since all it does is make them feel like failures as mothers. Which is not a good state of mind to be in when someone just dumped a new born baby in your lap and basically says "here you go, this human being lives or dies based solely on your actions".
Guilt can certainly be an unfortunate consequence. Much like how a blind person must feel every day as they're reminded how difficult life is for those who can't see.
Empowering people with information about ways they can improve the chances their offspring will have in life is definitely the most important message I got from the article.
If we want to encourage more women to breast-feed then tell them how much weight they will lose. Based on my observations breast-feeding is like having your own personal liposuction machine.
More seriously we need to help women breast-feed if they want without making them feel like failures or bad mothers if they don’t. It is a hard problem, but one that is worth trying to come up with a solution.
The 1-3 point IQ advantage is widely and consistently reported in the literature, and it's probably right as far as it goes. However, studies that additionally adjust for socioenvironmental factors (mothers who breastfeed are more likely to read to kids, have larger vocabularies, etc), show results around 1 IQ point: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1633786.
The "mothers should have the option" bit in the article was really off-putting. As if taking the option away was even on the table! It bears keeping in mind that the vast majority of the current adult generation was formula-fed. In 1971, only 25% of kids were breastfed in the hospital, and only 8% were still breastfeeding at 3 months.
As a metacomment, recommendations having to do with parenting are myopic. They lack any semblance of cost-benefit analysis, and the attitudes in the medical community about how women should mother date back to a time when womens' opportunity costs for labor-intensive parenting choices were nothing.
Also often ignored is how these choices affect fathers. Breastfeeding removes the father's ability to independently take care of an infant. Because feeding is a bonding experience, this creates a dynamic where the child looks at the mother as the last line in being comforted. This is a choice couples can make, but it is one that involves trade offs, which the medical community ignores. It would be one thing if they just left it to patients, neutrally presenting the data and letting parents evaluate the trade-offs. But they tend to hide the data and aggressively push their interpretation of the proper trade-offs.
> Breastfeeding removes the father's ability to independently take care of an infant. Because feeding is a bonding experience, this creates a dynamic where the child looks at the mother as the last line in being comforted. This is a choice couples can make, but it is one that involves trade offs, which the medical community ignores.
What about a breast pump? As long as some lactating female provides milk, the milk can be frozen for months and is nearly as convenient as formula for a father.
Also FWIW men can lactate if appropriate hormone injections are given.
I was almost completely unable to feed my daughter, who was breastfed; my wife expressed and bottled, but my daughter wouldn't accept it. It was a pretty upsetting dynamic at the time; it kept me from being comfortable watching her for any significant length of time.
My understanding: not an uncommon predicament.
If there was a long term consequence, though, (she's 13 now), I haven't detected it.
> What about a breast pump? As long as some lactating female provides milk, the milk can be frozen for months and is nearly as convenient as formula for a father.
There have been few (if any?) studies that look closely at breastfeeding vs bottlefeeding pumped milk. Our society has jumped on the "pump and bottle" wagon because it's seen as a viable way to allow women to go back to work sooner while still "breastfeeding", but it's not known if this actually has the same effect.
Does the increase in IQ/whatever come from the nutritional content of the breastmilk? Does it come from antibodies or other contents that might be impacted by refrigeration/freezing followed by reheating? Does it come purely from the emotional bonding that breastfeeding promotes? We don't know, because we don't even know why breastfeeding is better than formula, and we're basically giving medical advice blindly when it comes to pumping.
But for what it's worth, the difference is so small as to be pretty meaningless. The "gap" is going to be dwarfed by other factors, both genetic and environmental.
I think in practice that's more of a way to "include the father in the process" than genuinely have him offload a task from the mother. I think for many if not most couples, it's almost as much work as breastfeeding and bottle feeding combined.
Perhaps... but my larger point is that a father doesn't have to decide to check out of the responsibilities in order to have his kid breast fed. Thanks to breast pumps a working mom can manage it, and there is a market for fresh breast milk sold by lactating mothers who have a surplus.
Thanks for the data, and I agree with your other comments in general. Articles about these studies pretty much always oversimplify the calculus.
I'll add that besides paternal involvement, maternal stress over societal pressure to breastfeed if it's not working out for some reason can certainly be worse for the overall outcomes than the loss of breastfeeding.
I'm glad that this study apparently included socioeconomic factors, but my instinct is that there are many other factors being left out. What are the correlations with maternal work schedules, time spent bonding with the child in other ways, etc? My guess is that other potential impacts on IQ and long-term outcomes not considered by this article also correlate with the breastfeeding/formula decision.
>Also often ignored is how these choices affect fathers.
My wife and just adopted and its hard not to feel second class when there's all this horse wisdom about breastfeeding, which just isn't an option for us. Thankfully, I don't see 1-3 IQ points as having any practical advantage. I could see perhaps 10+ as being meaningful. We're not even sure what IQ measures other than the ability to take IQ tests. I'm not saying the test is useless, but its a synthetic benchmark and the realm of 1 to 3 points may be meaningless itself, even though its measurable, the same way spending an extra $200 on my desktop will mean my games will go from 45fps to 60fps. I doubt I'd notice.
Its also bothersome that IQ is the only metric social and biological sciences take seriously. I'd love to see the results of different lifestyle choices on things like emotional intelligence or creative intelligence.
"Breastfeeding removes the father's ability to independently take care of an infant."
This whole mammal thing is seriously backwards then. We should have evolved from snakes (whose offspring takes care of itself completely independently which supposedly is an excellent kind of dynamic.)
Also father of 2. Wife breast-fed both kids to about 14 months. I frequently gave a bottle (of breastmilk) to the first. Second wouldn't take the bottle at all. I never felt left out of the process. I changed (and still change) diapers and contribute in other ways. Mommy mostly handled bedtime until breastfeeding was over - now I frequently handle bedtime. With the second child, during the first year I handled most of the first-kid duties while my wife took care of the baby. I don't see a problem with this at all. My kids (5 and 1) are always excited to see me when I get home, so much so that my wife is more likely to feel left out than I am. Insinuating that breastfeeding causes kids to look to the mother as the last line of comfort is ridiculous in my opinion. Women are literally MADE to do this and I don't care what modern "gender equality" proponents might make of that statement.
Edit: I do want to qualify by saying that I do recognize that it's not possibly for every mother to breast feed and I'm not even trying to argue that breastfeeding is superior. I only take issue with the idea that breastfeeding negatively impacts the father's participation.
> Women are literally MADE to do this and I don't care what modern "gender equality" proponents might make of that statement.
That's a fallacious, appeal to nature argument. People should raise their kids how they want, and should feel free to make their parenting choices rationally. What's "natural" or what women are "made to do" shouldn't enter into the equation. "Naturally" something like 1 in 25 women died of childbirth.
There are good reasons to breastfeed. But there are also good reasons not to breastfeed. My wife and I bottle-fed from early on. I did all the night feedings, because I handle interrupted sleep better than she does. At the same time, I have little patience for after-work playtime, and am happy to let my wife handle that. It's an arrangement that takes advantages of our relative strengths that would not be practical without infant formula.
There are considerable benefits to breastfeeding, so while it's totally the mother's choice and we should avoid undue pressure it's wrog to say that there are only small benefits to breastfeeding.
I would put "huge benefits to breastfeeding" right up there with medical myths that have been recently debunked, such as "dietary cholesterol raises blood cholesterol" or "salt causes hypertension."
While the article does acknowledge that the study only shows correlation and not causation, it doesn't suggest what seems to me the most intuitively obvious alternative hypothesis.
We know that increased rates of mental stimuli and social interaction are beneficial to a growing brain. Perhaps breastfeeding correlates with parents that have more free time to interact with their child.
The actual paper contains much more information than this BBC article. I'm not sure why they didn't link to it, but here is the original paper at the Lancet [1] as well as the full-text pdf file [2].
Researchers have considered your hypothesis. There have been many attempts to eliminate confounding variables in these studies (this doesn't mean that they were necessarily successful in doing so, but they did think about it). Often they attempt to control for differences in parenting styles, which should cover how much time they spend interacting with their child.
Also until 6-10 months, babies can't hold their own bottles, so someone is probably still interacting with them (unless you prop up the bottle and leave the baby alone, which is possible but not recommended).
It interests me that the conclusion of these studies is almost always presented as breastfeeding increasing IQ (or conveying health benefits or whatever). Surely, breastfeeding is the norm, and this headline should be "Bottle feeding linked to lower IQ"?
Reframing it like that makes it seem like parents who formula-feed (because you can pump breast milk into a bottle) are harming their children.
There's already enough pressure on women to breast feed and I'm not sure it's useful to put more on. It'd be better to make sure women can get rapid access to breast feeding consultants.
>makes it seem like parents who formula-feed are harming their children
Well, if the studies are to be believed, then that's exactly what is happening. I completely understand the "pressure on mothers" argument, but I'm not sure that really flies, especially given the (albeit more subtle these days due to legislation) opposite pressure put on mothers by Nestlé and the rest.
I also find the fact that initial breastfeeding rates vary so wildly by country (from 98% in Sweden though to 57% in the US) interesting, and again more likely to do with commercial and social pressures of the same kind than to do with physical differences between mothers worldwide. While-ever the argument is presented as "Breast is Best" rather than "Artificial is Worst", I suspect this will continue.
I suspect that socially progressive Sweden makes it easy to breastfeed while repressive US (Facebook bizarely banned photographs of breastfeeding mothers) doesn't.
Breastfeeding has not always been the norm. At least in the US in the 70s doctors' advice was strongly against breastfeeding and encouraged switching to formula as soon as possible.
I definitely take studies like this with a grain of salt, though I do find them interesting. This one does appear to be from a sufficiently large sample size.
Besides this, though, I find it interesting that humans feel they can sufficiently reverse engineer breast milk to replicate the health benefits. Not saying at all that eventually this won't be possible or probable.
But the "original formula" has gone through at least tens of millions if not hundreds of millions of years of evolution. From this respect I'm in complete awe that we have this nature-given tool, and astonished that more humans don't do this for their children.
> I definitely take studies like this with a grain of salt
as everybody should, the problem is the media publishing these stories know that the only thing people read are the headlines.
> Experts say the results, while not conclusive ...
The article says one thing and its opposite. The goal here isn't to inform but to distract. Absolutely no conclusion can be made out of reading this article.
Maybe but it certainly is linked to epic levels of smugness and superiority complexes on the part of the parents and healthcare system. At least here in the UK.
My oldest is quite intelligent. We've had "I bet she was breast fed" more times than I can count. The reply is "no, it's a combination of genetics and nurture"...
Even the most generous estimates are that breastfeeding adds a few IQ points. Definitely not noticeable for an individual.
However, at the population level, which is what the healthcare system is dealing with, that's a huge deal. Imagine if the average IQ of the entire population were shifted up by several points.
Imagine if the average IQ of the entire population were shifted up by several points.
I guess it depends on the starting point. I imagine that shifting the average from 85->90 would have a much bigger effect than shifting from 105->110. Most studies seem to show a pretty sharp diminishing returns when correlating IQ points to just about any measure of 'success'.
Isn’t this the effect of removing lead from the environment? People with high IQ’s don’t see the value of a few more IQ points (marginal utility), but when you have an IQ of around 80 then every point makes a huge difference.
>Maybe but it certainly is linked to epic levels of smugness and superiority complexes on the part of the parents and healthcare system. At least here in the UK.
Not sure the UK has a "smugness and superiority complex" problem. It sure has a "let's not allow anybody be different/at a higher level" problem though. Everybody is labelled "smug", "pretentious git" etc.
I mean, complaining about people breast-feeding being smug?
Well that's a meta argument if their ever was one and a good point.
Let me summarise at a more abstract level; people are eager to differentiate from others because to be honest we're pretty boring and uninterestif, myself included. They do this by clinging onto all sorts of irrational non-scientific beliefs. Some of these become almost ritualistic'(squirting breast milk on a child's head rather than using dentinox to cure cradle cap). Then these beliefs turn into packs and factions primarily for maintaining supposed differentials and rituals. Other people don't care (like myself) but are somewhat vexed at the suggestion our time needs to be wasted on such things at every available opportunity. This is a bad human trait that manifests itself in many ways.
This is something people have been going back and forth about for decades. There's even been a study that used more people and was randomized and controlled. You can read actual literature surveys of all the ways parents can affect their kids' IQs here: http://squid314.livejournal.com/346391.html
It's already known since a while that breastfeeding is a reason for a higher IQ. There was a study in 2007 that the correlation between breastfeeding and the IQ is moderated by genetic variant in FADS2.
Breast milk and colustrum is already sold, both in healthcare (eg premature babies) and leisure (a short lived experiment saw a London cafe selling breastmilk icecream).
After reading the article I did some very quick computations and my finding based on the model I developed is that children who were not breastfed have an IQ impairment in the 1-3 IQ points range, after accounting for confounding factors.
This is very consistent with the results published here.
Compared to this study, I believe the methodology I'm using is more powerful for three reasons:
- much larger sample size: the dataset I have access to comprises 12015 children, compared to 3493 for the study
- a larger set of confounding factors is accounted for: notably, the data includes height and weight measurements at up to five points in time
- confounding factors are fully accounted for, rather than hand-waved away. This is a complex model based on random forests and linear model, and the results are entirely cross-validated.
Stay tuned for more detailed computations. I will also ask the organizers for the exact definition of breastfeeding used.
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Edit:
On the other hand, the study is still very appealing because according to the authors, there is little correlation between demographics and breastfeeding in Brazil, whereas the validity of the effect I'm reporting is dependent on whether the demographic model is powerful enough to remove the correlation. Still, I believe most of the correlation is easy to remove, and it isn't clear that there aren't subtle demographic effects even in Brazil. In particular, the proportion of participants with missing IQ data seems to decrease with duration of breastfeeding, and I don't know if they have an explanation for that.