I’m assuming (but not 100% sure) this is related to the baby formula issues discussed in Inadequate Equlibria?
We don’t even have a good way of comparing formula to breast milk. Everything is confounded. Nothing is controlled.
Hmm. To make sure I understand: you could randomize babies getting formula vs breastmilk, but if you have reason to believe formula is bad for babies it’s particularly unethical. And there are people who breastfeed and people who use formula that you could run a study on, but the people who self-select into formula and breastmilk have all sorts of confounders? (Makes sense, although I notice I’m not actually sure I could predict whether, say, poor mothers are more likely to breastfeed or to use formula)
It still seems like a situation where there should be enough families using each that you can attempt to control for confounders.
You can do an encouragement design similar to what was done in Belarus by randomizing some hospitals to adopt breastfeeding-friendly policies and some to not adopt them. Unfortunately, since not all parents in a breastfeeding-friendly hospital will breastfeed and not all parents in a control hospital will use formula, and since you’re randomizing at the hospital level, your sample size has to be huge to detect any effect. And because many of the outcome variables you’re interested in are long-term (IQ age seven, for example), you have to follow people for a long time. It’s very very expensive and it takes forever.
The Belarus results are IMO the strongest results we have about the benefits of breastfeeding, and show a huge rise in IQ from three months of breastfeeding. Of course, as this post points out, the top formula brands have improved their product in the past decade, and modern babies may receive better milk than the babies of the Belarus study. ¯\_(ツ)_/¯
Ozy—sibling studies have a major problem—they don’t take into account the reasons why a mother would breast-feed one child but not the other. If you ask moms about this, they always have an answer, and it is usually something like, ‘Josh was very sleepy and just wouldn’t suck. We had to give him a bottle to get him to eat at all.’ My mother basically gives this exact story for why I was breast-fed and my brother was not. And my brother had developmental problems and I did not. I don’t think this is because he was fed formula. Remember, weaker/sicker babies are more likely to get formula, and sicker/older/tireder/more depressed mothers are more likely to formula feed. In order to breastfeed, everything has to go right. One thing goes wrong, and it’s on to formula.
I think the point here is that there are many circumstances that can influence the choice to use formula, and these might have a stronger effect than the choice itself.
But population-level differences in populations that were encouraged to breastfeed vs. not encouraged to breastfeed, as in the Belarusian study, should circumvent that.
“Sites were randomly assigned to receive an experimental intervention (n = 16) modeled on the Baby-Friendly Hospital Initiative of the World Health Organization and United Nations Children’s Fund, which emphasizes health care worker assistance with initiating and maintaining breastfeeding and lactation and postnatal breastfeeding support, or a control intervention (n = 15) of continuing usual infant feeding practices and policies.”
There have been a number of randomized trials of breast feeding vs formula. I personally know a mother who was randomized c1980. She was not happy when she learned that the hypothesis being tested was that formula had a (specific) negative effect. Which it didn’t. No RCT has found any effect. However, the RCT have been very wasteful. They should treat randomized children as a valuable resource, like a twin registry, to be followed for years and extensively measured, but they don’t; indeed, I don’t think they’re allowed to contact them again.
I don’t see how it’s possible to really randomize this. No one’s going to stick with a feeding method if they think it’s best for their child to switch, just because they signed a form telling some researcher they would. Baby sleep studies have the same problem.
As far as I know, the closest we have is the Belarusian PROBIT study (as Ozy mentioned above) where it was advising that was randomized.
Do you apply this skepticism to all non-blind randomized studies? If people have an opinion on the right thing to do, they don’t join the study. And studies do ask people if they followed the instructions.
I’m not talking about blinding, I’m just talking about randomizing. That’s right, in areas with obvious confounders like class, baby health, and maternal stress level, and relatively small differences in outcomes between the groups anyway, I don’t think correlational data is worth much.
Having parented a difficult-to-feed baby and having tried everything I could think of to get calories into her, I’m quite sure that even parents who start out willing to follow a given recommendation quickly change their mind if things don’t seem to be going well. (If not, you’re selecting for parents who are willing to prioritize following instructions over their baby’s health, which certainly gets you a different population than is typical.)
It’s a mess. In general poor people are more likely to use formula since they have to go back to work/don’t have the same level of indoctrination- oops education—about the benefits of breast feeding, and breast feeding is a lot of work. Then there’s the issue that sicker babies often have to be formula fed, because they have weaker sucking reflexes and/or require special high-calorie formula. Multiples are more likely to be formula fed, for obvious reasons. Babies of older mothers are more likely to be formula feed, since older moms produce less milk, etc. etc. More obsessive and more highly educated mothers are more likely to breast-feed for obvious reasons. In general, my conclusion from the (noncomprehensive) reading I’ve done about it indicate that breast feeding clearly reduces early respiratory and GI infections as well as reduced colic and GI distress (while breastfeeding), but has unclear impact on long term psychological, physical, and cognitive health. Overall those things look better with breast-fed babies, but attempts to control for other things often negates the effects, leading to yo-yoing articles about the supremacy of breast milk depending on the fashion of the day. However, going back to theory, it would be very strange if breast milk weren’t better given human’s past experience with making food-substitutes. That being said, the healthiest baby is a fed baby, and the impact of formula vs breast feeding is unlikely to outweigh many other factors in a person’s life, such as milk production, needs to earn money to support the family, and mental health of the mother (depression in mothers is very highly correlated with poor long term outcomes).
Then there’s the issue that sicker babies often have to be formula fed...
Why do you believe this? My son is currently in the NICU (born at 25 weeks), and they push breast-feeding extremely hard, even going as far as to make it sound like negligence if you don’t attempt to breastfeed (due to higher incidences of NEC in premies, among other reasons). Babies whose mothers can’t breastfeed are supplied with donor milk, not formula. When my first son was born (who wasn’t a premie or otherwise sick), the nurses and doctors talked as if it were just a matter of personal preference.
My experience could be unrepresentative though, so I’d love to see some kind of justification for the above-quoted claim.
Sick babies are often too weak to suck much—and this is true even if the baby isn’t sick enough to require a nicu stay. If a baby has to be in the hospital—it can be difficult logistically to breastfeed them, and of course if women aren’t dedicated to it, they won’t maintain milk. My son was required to stay in the nicu for 4 days (for ridiculous reasons—he was fine). I was only allowed to stay in the hospital 2 nights, and I was exhausted and needed to sleep. I ended up allowing them to feed him formula since my milk was slow to come in—no one strongly encouraged me to stay there and breastfeed in the night. I got a 5 minute tutorial on how to use a pump, which was briefly suggested. It’s great that some hospitals are encouraging breastfeeding and providing donor milk to premature babies. I don’t know how universal this is. I know other women who have complained of similar problems I faced.
I’m assuming (but not 100% sure) this is related to the baby formula issues discussed in Inadequate Equlibria?
Hmm. To make sure I understand: you could randomize babies getting formula vs breastmilk, but if you have reason to believe formula is bad for babies it’s particularly unethical. And there are people who breastfeed and people who use formula that you could run a study on, but the people who self-select into formula and breastmilk have all sorts of confounders? (Makes sense, although I notice I’m not actually sure I could predict whether, say, poor mothers are more likely to breastfeed or to use formula)
It still seems like a situation where there should be enough families using each that you can attempt to control for confounders.
You can do an encouragement design similar to what was done in Belarus by randomizing some hospitals to adopt breastfeeding-friendly policies and some to not adopt them. Unfortunately, since not all parents in a breastfeeding-friendly hospital will breastfeed and not all parents in a control hospital will use formula, and since you’re randomizing at the hospital level, your sample size has to be huge to detect any effect. And because many of the outcome variables you’re interested in are long-term (IQ age seven, for example), you have to follow people for a long time. It’s very very expensive and it takes forever.
The Belarus results are IMO the strongest results we have about the benefits of breastfeeding, and show a huge rise in IQ from three months of breastfeeding. Of course, as this post points out, the top formula brands have improved their product in the past decade, and modern babies may receive better milk than the babies of the Belarus study. ¯\_(ツ)_/¯
Ozy—sibling studies have a major problem—they don’t take into account the reasons why a mother would breast-feed one child but not the other. If you ask moms about this, they always have an answer, and it is usually something like, ‘Josh was very sleepy and just wouldn’t suck. We had to give him a bottle to get him to eat at all.’ My mother basically gives this exact story for why I was breast-fed and my brother was not.
And my brother had developmental problems and I did not. I don’t think this is because he was fed formula.
Remember, weaker/sicker babies are more likely to get formula, and sicker/older/tireder/more depressed mothers are more likely to formula feed. In order to breastfeed, everything has to go right. One thing goes wrong, and it’s on to formula.
I’m confused—the Belarusian study Ozy is talking about wasn’t a sibling study, right?
I think the point here is that there are many circumstances that can influence the choice to use formula, and these might have a stronger effect than the choice itself.
But population-level differences in populations that were encouraged to breastfeed vs. not encouraged to breastfeed, as in the Belarusian study, should circumvent that.
Correct. I guess I’d rather have an appropriate quantification of the “encouragment” though; but I could be wrong, I will read the study design...
“Sites were randomly assigned to receive an experimental intervention (n = 16) modeled on the Baby-Friendly Hospital Initiative of the World Health Organization and United Nations Children’s Fund, which emphasizes health care worker assistance with initiating and maintaining breastfeeding and lactation and postnatal breastfeeding support, or a control intervention (n = 15) of continuing usual infant feeding practices and policies.”
There have been a number of randomized trials of breast feeding vs formula. I personally know a mother who was randomized c1980. She was not happy when she learned that the hypothesis being tested was that formula had a (specific) negative effect. Which it didn’t. No RCT has found any effect. However, the RCT have been very wasteful. They should treat randomized children as a valuable resource, like a twin registry, to be followed for years and extensively measured, but they don’t; indeed, I don’t think they’re allowed to contact them again.
I don’t see how it’s possible to really randomize this. No one’s going to stick with a feeding method if they think it’s best for their child to switch, just because they signed a form telling some researcher they would. Baby sleep studies have the same problem.
As far as I know, the closest we have is the Belarusian PROBIT study (as Ozy mentioned above) where it was advising that was randomized.
Do you apply this skepticism to all non-blind randomized studies? If people have an opinion on the right thing to do, they don’t join the study. And studies do ask people if they followed the instructions.
I’m not talking about blinding, I’m just talking about randomizing. That’s right, in areas with obvious confounders like class, baby health, and maternal stress level, and relatively small differences in outcomes between the groups anyway, I don’t think correlational data is worth much.
Having parented a difficult-to-feed baby and having tried everything I could think of to get calories into her, I’m quite sure that even parents who start out willing to follow a given recommendation quickly change their mind if things don’t seem to be going well. (If not, you’re selecting for parents who are willing to prioritize following instructions over their baby’s health, which certainly gets you a different population than is typical.)
It’s a mess. In general poor people are more likely to use formula since they have to go back to work/don’t have the same level of indoctrination- oops education—about the benefits of breast feeding, and breast feeding is a lot of work. Then there’s the issue that sicker babies often have to be formula fed, because they have weaker sucking reflexes and/or require special high-calorie formula. Multiples are more likely to be formula fed, for obvious reasons. Babies of older mothers are more likely to be formula feed, since older moms produce less milk, etc. etc. More obsessive and more highly educated mothers are more likely to breast-feed for obvious reasons. In general, my conclusion from the (noncomprehensive) reading I’ve done about it indicate that breast feeding clearly reduces early respiratory and GI infections as well as reduced colic and GI distress (while breastfeeding), but has unclear impact on long term psychological, physical, and cognitive health. Overall those things look better with breast-fed babies, but attempts to control for other things often negates the effects, leading to yo-yoing articles about the supremacy of breast milk depending on the fashion of the day. However, going back to theory, it would be very strange if breast milk weren’t better given human’s past experience with making food-substitutes. That being said, the healthiest baby is a fed baby, and the impact of formula vs breast feeding is unlikely to outweigh many other factors in a person’s life, such as milk production, needs to earn money to support the family, and mental health of the mother (depression in mothers is very highly correlated with poor long term outcomes).
Why do you believe this? My son is currently in the NICU (born at 25 weeks), and they push breast-feeding extremely hard, even going as far as to make it sound like negligence if you don’t attempt to breastfeed (due to higher incidences of NEC in premies, among other reasons). Babies whose mothers can’t breastfeed are supplied with donor milk, not formula. When my first son was born (who wasn’t a premie or otherwise sick), the nurses and doctors talked as if it were just a matter of personal preference.
My experience could be unrepresentative though, so I’d love to see some kind of justification for the above-quoted claim.
Sick babies are often too weak to suck much—and this is true even if the baby isn’t sick enough to require a nicu stay. If a baby has to be in the hospital—it can be difficult logistically to breastfeed them, and of course if women aren’t dedicated to it, they won’t maintain milk. My son was required to stay in the nicu for 4 days (for ridiculous reasons—he was fine). I was only allowed to stay in the hospital 2 nights, and I was exhausted and needed to sleep.
I ended up allowing them to feed him formula since my milk was slow to come in—no one strongly encouraged me to stay there and breastfeed in the night. I got a 5 minute tutorial on how to use a pump, which was briefly suggested. It’s great that some hospitals are encouraging breastfeeding and providing donor milk to premature babies. I don’t know how universal this is. I know other women who have complained of similar problems I faced.