Nursing doubts

I think breastfeeding is different because… public health people decided it should be, and we’ve internalized their messaging.

I haven't gone around and checked much, but my gut impression isn't that this is about public health people. I think it's more like a Chesterton's Fence backlash against previous generations' experts claiming that formula was obviously better. IIRC, mothers were warned against using breastmilk and told to go to formula instead, because it's Scientific™. So it took some cultural pushback to reclaim evolution's solution to feeding newborns.

I'd like to add some context to the "pressure to breastfeed" argument, especially regarding the history, which is missing from these experiments.  In the 1970's Nestle launched a worldwide marketing campaign promoting formula feeding as better than breastfeeding.  With big money behind the campaign and profit incentives, it was effective.  This resulted in numerous bacterial illnesses and child deaths in Africa as the water being used was contaminated.  Nestle had no reason or fiscal incentive to educate people in local communities or supply clean water.  The controversy with formula is often not framed as one about private sector incentives and how profit margins dictate sales tactics.  After this major f up in Africa, corporations were somewhat more careful. However, even today, they will inundate expecting mothers with formula samples.  This is strategic.  It's observational, but I'm willing to bet that most new mothers hold on to the samples, "just in case," even if they intend to breastfeed.  Breastfeeding is difficult for most women in the first few weeks, causing pain and discomfort.  The companies understand that during this time of vulnerability, one might reach for the samples to get a reprieve.  The more often you do this, the less milk you produce, until you end up effectively nudged to make the switch.  The facts and figures shared here assume that we are all acting as "rational man" weighing the pros and cons of breastfeeding and the impact of child wellbeing.  There is an underlying profit motive to formula that does impact our behavior on this issue through our interactions with formula companies.  Our decisions are not always made in a rational manner. It is worth understanding the context behind why some people are very passionate about the breastfeeding debate.  And yes.. it is cheaper.

Curation notice: a good old fashion fact post. It's relevant, detailed, and legibly written.

Is 3.1 points small? Well, a 100 IQ is higher than that of 50% of the population, while a 103.1 IQ is higher than 58%. Adding 3.1 IQ points to a kid ranked 13th in a 25-person class would push them up to around 11th. And, personally, if you were going to drop my IQ by 3.1 points, I would not be super stoked about it.

And remember, 3.1 points is still just the impact of a modest increase in breastfeeding intensity. If you ran a trial that compared no breastfeeding to exclusive breastfeeding for 12 months, the impact would surely have been much larger.

For context, in high-income countries lead poisoning is estimated to have lowered IQ by a comparable amount (the paper doesn't explicitly state the IQ drop, but does say that the mean blood lead level in HICs is 1.3 μg/dL and provides the chart below), and lead poisoning is taken pretty seriously. 

My background: My mother was a lactation consultant educator. As a teenager I was the tech support for her lectures, keeping the then early tech of computer projectors working properly for her. I would just read a book while she lectured, but I say through so many lectures it eventually sunk in anyway. She eventually started trying it her new tests on me, knowing that if I did poorly the test was too hard.

So here are some key points I want to make, not in favor of breastfeeding exactly (although I do think it's good, and that breastmilk is good!), but in favor of making it easier.

1. Some women just have a really hard time producing milk. That's ok! You can still get nearly all the benefits without breastfeeding, by using a breastmilk bank! Some women overproduce milk, and for their own health must pump it out. Some of them donate this excess milk to a breastmilk bank for others to use.

2. It shouldn't be painful. If it is, something is wrong and you should seek support from a lactation consultant. Don't trust doctors with this, most are clueless about breastfeeding and will give actively harmful incorrect advice. My rough estimate is that 90% of women should be able to breastfeed without pain (if given correct advice and guidance), and the remaining 10% should just give up and use a breastmilk bank. In our well-fed modern society, overproduction is quite common. As a community we produce more way more breastmilk than we can use!

3. There are a lot of technical details, and getting them right matters. If done incorrectly, things can start to go wrong. If you correct this quickly, within the first couple days, you'll be fine. The longer you let things go wrong, the worse it gets. Women who've been doing things slightly wrong and hurting themselves for many days are in for a load of trouble. The problems compound and become increasingly bad, and the recovery will be painful whether you decide to continue breastfeeding or not. Get help early and often!

4. A good quality breastpump makes a big difference. There are tons of shoddy ones, so getting advice on which ones are good is important. They can cost several thousand dollars, but are fully cleanable, so many women choose to rent (since they only need them for a year or two).

5. The first few weeks are indeed much more important. Aim to give breastmilk at least for the first couple months, ideally. Again, it doesn't need to be your breastmilk, use a bank if needed!

6. If possible, talk with a lactation consultant before giving birth. There's a lot of technical details to learn, and getting it wrong hurts! If you have had breast surgery, you definitely want to talk with a lactation consultant. A lot of plastic surgeons are clueless about mammary glands and unnecessarily mess stuff up in there. Another potential problem you might notice before giving birth is if your breasts are still smallish in the third trimester. There's a chance you will underproduce milk, and you be prepared to have that be only a portion of your babies calories. You can supplement with a breastmilk bank and/or formula. Don't use a standard bottle to supplement though if you plan to also breastfeed, instead you need to use things that won't teach the baby bad nursing habits.

Other health claims: breastfeeding slightly reduces risk of breast cancer in the mother and increases chance of colorectal cancer and breast cancer in the child.

The advice we were given was "Fed is best".

However, we also very much wanted to breastfeed, primarily due to convenience and cost.

Getting started was very difficult. We used a small number of premixed formula bottles, two of which were "free samples". We almost gave up.

A lactation consultant helped us find a comfortable position, and eventually ended up with the "rugby hold", which makes no intuitive sense whatsoever - the infant is held under the arm, legs almost behind the mother.

Once started, breastfeeding turned out to have several clear advantages, some of which were very surprising to us:

1. Low poo volume. Breastfed babies produce very little poo early on, as almost everything is absorbed. Formula produces a lot more poo. (This is apparently well-known among midwifes & health visitors, but not mentioned until we actively asked)

2. Low to no poo stink compared to formula. (Anecdotal) In discussion with other parents we found that the formula fed infants poo smelled a lot worse, even accounting for volume and parental preference (your own child's poo stinks less than that of all other children)

3. Reduced rate of constipation. Formula fed infants are at a much higher risk of constipation, as a side effect of the above.

4. Reduced posseting. Bottle fed infants swallow a lot more air due to the mechanics involved, which makes them need more burping and bring up more milk when they do. Obviously this is due to the bottle itself rather than what's in it, but formula fed is 100% bottle while breastfed is some lower percentage.

5. Night feeds didn't require full waking. The mother can do it half asleep and the infant is fed almost instantly, as mentioned elsewhere. However, this can only be done by the breastfeeding mother. The partner cannot assist.

6. (Anecdotal) Flying was easy. When disturbed, simply insert nipple and infant is immediately calmed. However it is possible a pacifier would work similarly well for a bottle fed infant.

The benefits of breastfeeding may be somewhat lower for the median reader of this blog than the median late 1990s Belarusian. You probably have access to cleaner water, more/better medical care and newer formula that includes things like DHA, ARA, and more nucleotides.

Why somewhat? It's plausible to me that even just the lack of DHA would give the overall RCT results.

On priors I'd expect formula to be worse: there are strong evolutionary reasons for breast milk to be the ideal food, while formula is limited by our capability to understand what babies need. If we were missing something important in formula to where babies were dying early we'd notice, but as the effect size gets smaller the chance we notice goes way down. But running studies and updating our practices based on them is still a factor, and DHA is mandatory (in the US) now. I'd still guess that an RCT today would show IQ impacts, but this is based on priors about how hard this problem is, our civilizational capacity, and the incentive structures for formula manufacturers, and not primarily on an RCT in quite a different environment.

Back when my co-parent & I were navigating these decisions 6-10 years ago, we came across a study that really shaped our thinking: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4077166/. Basically, the researchers analyzed outcomes in families where the siblings were breastfeeding-discordant. The punchline: "Once we restrict analyses to siblings and incorporate within-family fixed effects, estimates of the association between breastfeeding and all but one indicator of child health and wellbeing dramatically decrease and fail to maintain statistical significance."

It's only a single study, but it takes a fairly unique approach to addressing the issues in observational research on the topic, and as such, we weighed it pretty heavily in our decision-making. It's also worth keeping in mind that parental happiness and mental health makes a difference, and breastfeeding was very challenging to my co-parent from that standpoint (although the details are another story).

The RCT doesn’t sound properly randomized if people were deciding themselves whether to listen to the advice? Perhaps people with higher IQ listen to the intervention better. And then we just see the genetic correlation.

The LessWrong Review [? · GW] runs every year to select the posts that have most stood the test of time. This post is not yet eligible for review, but will be at the end of 2025. The top fifty or so posts are featured prominently on the site throughout the year.

Hopefully, the review is better than karma at judging enduring value. If we have accurate prediction markets on the review results, maybe we can have better incentives on LessWrong today. Will this post make the top fifty?

One more practical reason for breastfeeding is that it is convenient. Imagine that a baby starts crying at night.

1. Start breastfeeding. The baby is calmed immediately. You can stay in the bed. 20 minutes later you can both sleep again.
2. Go prepare a formula. You need to get out of the bed, prepare the formula, check the temperature. Meanwhile the baby is crying. That makes both of you more awake, so when all is done, it is not sure that both of you will fall asleep quickly.

Similarly, when you go outside your home. How convenient is it to breastfeed, vs prepare the formula?

To consider the cognitive development of a child is to delve into a deeply intricate process, one that evolves from kinesthetic experiences, through a kinesthetic-auditory phase, and eventually to a primarily visual mode in adulthood. This progression is not just a sequence of developmental stages but a roadmap to understanding the profound ways in which human perception and cognition are shaped by sensory interactions.

From conception to around the age of three, a child's brain is particularly attuned to sensory inputs, with a strong emphasis on tactile and kinesthetic experiences. The neural landscape of a child’s brain at this stage is heavily interconnected with their fingertips and mouth, areas densely packed with neurons. The importance of touch, smell, and texture cannot be overstated—they are the primary means through which infants engage with the world. It is through touching various surfaces, feeling different textures, and experiencing a range of smells that their neural pathways are actively molded and shaped.

Consider, for instance, the tragic 20th-century experiment where infants in orphanages were left in cribs without any physical interaction or emotional engagement. Despite adequate nutrition, many of these children suffered from severe developmental issues, and some even died. The absence of maternal touch and attention—a stark deprivation of kinesthetic and emotional stimuli—had devastating consequences, underscoring the critical role of sensory interaction in early development.

Thus, to understand infant cognition and development, we must strive to recreate a holistic environment that mimics the natural, nurturing surroundings of a caregiving woman. This means that researchers should design studies where the caregiver—ideally a person with a genuine emotional connection to the child, like a grandmother—provides not just sustenance but also tactile and auditory stimulation. The entire process of holding the child, feeding (even if with artificial milk), and engaging through touch, sound, and smell is likely crucial to normal development. The caregiver’s authentic, attentive presence might be just as important as the physical care itself.

Even culturally revered images, from the Madonna and Child to the Pietà, emphasize this tactile, kinesthetic connection. These iconic representations resonate deeply, especially with post-Christian societies, because they reflect an innate understanding of the primal importance of touch and physical closeness. This kinesthetic intimacy is foundational, particularly in early development, before the shift towards a more visual and abstract mode of cognition that dominates later educational stages.

By the time children enter school, their cognitive focus shifts, favoring visual and discrete information processing due to its efficiency in transmitting and analyzing data. This transition often creates a bias in researchers who, due to their own cognitive frameworks, may find it challenging to empathize with the significance of tactile and kinesthetic experiences in early childhood. However, this shift should not be allowed to overshadow the profound importance of early sensory experiences in shaping diverse cognitive pathways.

This perspective is informed by works such as Masaru Ibuka's Kindergarten is Too Late!, Dick Swaab’s We Are Our Brains, Robert Sapolsky’s insights on behavioral psychology, Allan Pease’s exploration of body language and age-related perceptual changes, and Richard Dawkins’ The Selfish Gene. These sources collectively highlight the vital role of tactile and sensory elements in early human development, suggesting a richer, more nuanced understanding of how we learn to perceive and engage with the world.