We’ve all heard the phrase breast is best. But is it really that simple? In this episode, I sit down with an expert to talk honestly about what the research actually says about breastfeeding and where the science gets murky.

We break down what’s fact, what’s myth, and why so much of the “breast is best” messaging comes from data that’s more correlation than causation. From IQ to obesity to immune health, we unpack what studies really measure (and what they don’t).

I also share my own story as a pediatrician who planned to breastfeed but ended up formula-feeding my son after a difficult birth and ICU stay. That experience shaped how I talk to parents today because feeding your baby should never come with shame.

We discuss:

• Why most breastfeeding research isn’t based on randomized trials

• How socioeconomic factors shape the data we see on long-term “benefits”

• The difference between short-term and long-term outcomes

• What sibling studies tell us about IQ, weight, and immunity

• Why guilt over feeding choices can actually take away from connection

• The importance of supporting all feeding journeys—breast, bottle, or both

Want more? Listen to the full, ⁠original episode⁠.

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00;00;00;01 – 00;00;21;17

Dr. Mona

Welcome back to the PedsDocTalk podcast. You are listening to the follow up. Where we revisit a favorite episode in less time than it takes someone to defend their infant feeding choice. Breast formula, combo feeding. It’s all judged and honestly, do you? Here’s why I say that a lot of breastfeeding research doesn’t tell the full story. Most studies aren’t randomized.

 

00;00;21;17 – 00;00;42;25

Dr. Mona

They compare groups of mothers who are already very different by income, education, work flexibility, and health status. So it’s nearly impossible to separate what’s due to breast milk itself from everything else that comes with being a parent. For example, a kid on formula getting a lot of ear infections. Well, are they also in daycare? Breastfed kids who has no diabetes as they get older?

 

00;00;43;02 – 00;01;05;10

Dr. Mona

Well, what is the family history and also the nutrition like when they start solids? Now that doesn’t mean breast milk isn’t amazing. It truly is. It changes composition when your baby or you are sick, supports the developing immune system and provides antibodies made just for your baby. Those are real benefits. But when it comes to claims that breastfed babies are healthier long term, the evidence just doesn’t back that up once you account for all these other factors.

 

00;01;05;17 – 00;01;24;13

Dr. Mona

And I see it every day, both as a pediatrician and as a mom. My husband and I were formula fed. Our two kids, one formula fed, one I exclusively pumped and both thriving in the same loving home. And the same holds true for the thousands of families I see in my practice. What really helps kids thrive isn’t just how they’re fed, it’s the environment.

 

00;01;24;13 – 00;01;47;29

Dr. Mona

They’re raised in a home filled with love, connection, enriching play, balanced nutrition when solid start, and opportunities to move and explore. That’s why I wanted to revisit this episode. Is breast really best with Emily Oster, economist mom and author of the bestselling book Crib Sheet. We’re breaking down what the data really shows about breast feeding, and why the best choice is the one that works for your family.

 

00;01;48;02 – 00;02;12;19

Dr. Mona

And you know what you need to do. Make sure to subscribe. Download and share this episode. That’s how the show grows and how I can keep bringing you these amazing conversations. And if you want the full episode, make sure to check the caption. Tag us while you listen at the Dog Talk podcast and at Prof. Emily Oster. Let’s get to it.

 

00;02;12;21 – 00;02;17;17

Dr. Mona

So what do you think the limitations of breast milk and breastfeeding research are?

 

00;02;17;19 – 00;02;44;04

Emily Oster

So I think the biggest limitation is that for the most part, the data that we have on this isn’t from, Rand, like what we call randomized trials. And so most of the evidence that you see about breastfeeding is really like comparing, babies from moms who breastfed and moms who did not. And, but those groups tend to be pretty different in, in a lot of other ways.

 

00;02;44;04 – 00;03;02;04

Emily Oster

So the most obvious one is that on average, women with more education breastfeed more than women with less, education. And that’s been true for a long time. There are there are other differences, across these groups. And so I think, you know, it’s really hard to separate the breast milk from all of the other things that are that are different.

 

00;03;02;04 – 00;03;08;28

Emily Oster

And that’s kind of a canonical problem in a lot of things here. But it really, really, really rears up in the case of breastfeeding.

 

00;03;09;01 – 00;03;16;09

Dr. Mona

So let’s talk about some of the general findings on the benefits of breast milk. What have you researched and obviously talked about in your book as well.

 

00;03;16;10 – 00;03;35;23

Emily Oster

So there’s kind of like the short run benefits. So things like, you know, like breastfeeding is like good for infant health in the first year, you know, things like digestion or ear infections and stuff like that. And you know, we can talk about it more, but that’s kind of a place where there’s probably is a bit, a bit better evidence of at least maybe some small positive effects.

 

00;03;35;25 – 00;03;59;21

Emily Oster

And then there’s a whole category of things which I think are in many ways, the pieces that kind of stress people out the most, which is this idea that, like, there are these long term effects of breastfeeding that, you know, breast milk kids who are breastfed are going to be smarter, they’re going to have higher IQs, they’re going to be thinner, or they’re going to be getting sick less, in, you know, when they’re older, they’re going to have all kinds of like long term.

 

00;03;59;23 – 00;04;15;13

Emily Oster

There’s gonna be all kinds of long term stuff, that where there are benefits. And I think that’s what a lot of moms here, you know, you have to give your kid the best start. It’s the best. It’s the best. And, you know, if you don’t like, you know, you’ve sort of failed at this first thing, that you’re supposed to be doing.

 

00;04;15;13 – 00;04;20;04

Emily Oster

And, that stresses a lot of people stress me out. I don’t know if it stressed you out.

 

00;04;20;06 – 00;04;41;25

Dr. Mona

Oh, it did, but you know what? It did stress me out. But because I understand the limitations of the research that you just mentioned, I know that yes, there is a small, small benefit for breast milk that we of course understand that it’s from mom. It’s breast milk does obviously, when a child sick mom’s breast milk changes to, you know, nourish that child for their needs.

 

00;04;42;00 – 00;05;08;07

Dr. Mona

If mom is sick, the breast milk can change. I mean, we know that that that is an awesome thing about breast milk. But when you look at the long term implications, like you mentioned, I know many formula fed babies who did not have obesity, who don’t, who are very high IQ, who don’t get sick a lot. So we talk about IQ, and you said it perfectly that when they do the research studies, they’re not looking at the IQ of the parents per se.

 

00;05;08;07 – 00;05;36;15

Dr. Mona

Right. Maybe the breastfed moms were higher IQ to begin with. And maybe the formula fed moms had a slightly lower IQ. Understanding socioeconomic levels, understanding the people who do breastfeed. But what about a family like ours who is a two doctor family who? You can say that we probably have a pretty decent IQ formula, said their child. We’re not understanding the genetics that come in to our intellect, to our weight, to our immune system.

 

00;05;36;20 – 00;05;55;28

Dr. Mona

And that is not just how we are fed. And that is the big thing I want people to understand, because our son eats a variety of different foods, spices. That’s amazing for his immune system. Sure, he may get an ear infection, but I’m not going to blame it on the fact that I didn’t breastfeed my son because a lot of kids get ear infections, including kids who are breastfed.

 

00;05;56;05 – 00;06;19;06

Emily Oster

No. Totally. Right. And I think what really resonates there is, is sort of when you see this, when we talk about this, we we sort of people like talk about it as if the, the effects are like ignore even the the possible effects are enormous. And we sort of have to say, like, even if there was some small effect on IQ, which, just to be clear, not nothing in the evidence would particularly support it.

 

00;06;19;09 – 00;06;39;04

Emily Oster

It’s going to be tiny relative to the impacts of everything else about, you know, the genetics and the other things you do and all of the other things that happened to your kid. And like it, just like all of these things we’re talking about are really, really small. And and, you know, there are there are things sort of weighing in the other, you know, weighing in the other direction.

 

00;06;39;07 – 00;07;00;29

Emily Oster

And I think that sometimes we can get really wrapped up in breastfeeding with sort of like, well, I like I failed and then people can get very, can get very sad and it can really affect, you know, the way that they interact with the early period of their baby’s life when when you look back on it and you sort of think, I mean, you’re you’re still like a little your kids, still fairly little, like my kids are five and nine.

 

00;07;01;01 – 00;07;17;04

Emily Oster

And when I look back now, it’s like, and I look at their friends like nobody. I have no idea who was who was breastfed. This isn’t like this. This is seems so important in the moment. But in the in the aggregate, it’s it’s kind of like a, it’s a pretty small thing relative to every other thing.

 

00;07;17;06 – 00;07;46;15

Dr. Mona

And you said it perfectly like when you are so wrapped up in the decision, just so you made a choice not to breastfeed, and it was what you wanted to do. And that and the emotions that come with that. And if you are, you’re allowed to feel those emotions because I did too. But I want if you make that choice to formula feed and it was something that was hard for you, I want you to say, okay, I, I’m sad about this, but we’re going to move forward because if you like Emily said, like if you live in those emotions, you are taking away from all of the protective things that help enrich your

 

00;07;46;15 – 00;08;07;28

Dr. Mona

child. Like we said, developmentally engaging with your child, reading to them, talking with them, playing with them that is also very helpful for their development. The foods that we give them, everything that we do besides how we feed our babies. There are formula for breast milk in the first year or two of life is so much more protective and has a lot more of an impact on what Emily is saying.

 

00;08;07;28 – 00;08;12;12

Dr. Mona

Those long term things that the research is saying, and I can’t stress it enough.

 

00;08;12;12 – 00;08;26;09

Emily Oster

Yeah, I mean, I think some of my favorite, some of the best studies of this are things where they look at like two siblings, where one is breastfed and one is not. And, you know, you can think people are like, well, why would that happen? It’s like, well, I don’t know, like there was a medical issue. So you didn’t breastfeed one of them?

 

00;08;26;11 – 00;08;45;26

Emily Oster

You know, a medical issue with mom or, you know, it was the second kid and you didn’t do it or was a second kid, and you did do it. Just, you know, something, something happened. And and there you really don’t see any differences. So there’s two there are two siblings. You’re not seeing any differences in IQ in in obesity, any of these kind of things across the siblings in it.

 

00;08;45;27 – 00;09;04;29

Emily Oster

And it really, really does look like it’s sort of it’s differences across the moms, whether it’s in education or IQ or other things that are kind of driving the differences we see across families and within families. Those just sort of disappear. And I think that’s, you know, that’s pretty convincing evidence that there’s a lot of things that matter in your family.

 

00;09;04;29 – 00;09;09;13

Emily Oster

This particular thing is not driving those those outcomes.

 

00;09;09;15 – 00;09;26;09

Dr. Mona

I think that’s the message here. It’s my message is for, you know, if a breastfed mom is breastfeeding, I want you to know that that’s awesome. But if you choose to formula feed your baby, hey, that’s actually pretty awesome too, because there are other things that we can do. And that kind of is what made me feel comfortable with my choice.

 

00;09;26;09 – 00;09;44;07

Dr. Mona

I mean, I, as you know, I have that following on Instagram and so many mothers would message me or, you know, DM me and say, thank you for sharing your story about doing formula feeding. And I forget that it is kind of a story because it’s a choice that many mothers still feel guilty for. And I said, I am making the best choice for myself and for my son.

 

00;09;44;12 – 00;10;10;11

Dr. Mona

This is what I’m doing, and my story helps you make the choice and feel happy with your choice. That is what I want, because I don’t want parents to just feel and live in that guilt for so long, because their children will turn out awesome with the environment that they are in. Now, if you could design a study to assess the benefits of breastfeeding, what would you consider like if you were to, you know, kind of what we talked about rehash, how would you design a study or what would you consider in that?

 

00;10;10;13 – 00;10;33;00

Emily Oster

I think if I were to do a study, I think I would really focus on that, on sort of being in hospital, like providing support to help women, like continue breastfeeding even through it through a few weeks and then following up, really focus on some of this kind of early life health stuff rather than focusing on these long term things and, and try to see, you know, if we can kind of move the needle a little bit on on some of that.

 

00;10;33;00 – 00;10;44;27

Emily Oster

And honestly, like also help people who want to breastfeed but, but struggle to do it because I think the other thing we never talk about very much is like it’s actually really hard. Yeah. It’s just really hard. I fought a really hard.

 

00;10;44;29 – 00;10;47;25

Dr. Mona

And you said you did a mix, right? You did some pumping, some formula.

 

00;10;47;29 – 00;11;00;14

Emily Oster

Yeah, I think I, you know, with my, with my daughter, I did, I, we like, had a lot of, I had a lot of supply issues and so I pumped it, I fed her some and I fed her some formula. And my son, it was like a little bit easier because, I don’t know, it’s a second.

 

00;11;00;17 – 00;11;17;10

Emily Oster

It’s a second kid. But we still eventually, eventually did some formula because my, like, pumping supply just wasn’t that wasn’t that good. And I actually I, you know, I remember I felt like when we finally quit breastfeeding because he, he bit me, and I had, like, a negative reaction to it, of course, because he bit me.

 

00;11;17;14 – 00;11;32;25

Emily Oster

Yeah. And, and then I, and I sort of was like, and then he was just. And then basically after that he was like 9 or 10 months old, and he got really upset. And then that’s it. He would never do it again. And I remember like at the time, being really sad and being like, oh my God, I like did this thing.

 

00;11;32;25 – 00;11;46;28

Emily Oster

I shouldn’t have reacted like that. But now when I look back on it, it’s like, you know, from like now that like that’s a person who can read, you know, and it’s like it’s it’s just so not, you know, it sort of doesn’t have the emotional valence that it that it did.

 

00;11;47;00 – 00;12;05;01

Dr. Mona

Well, that’s a good example because I get that a lot in my office where I’ll have a mom come in who is is really not enjoying the pumping process, you know, trying to get what she can and the babies now, you know, eight, eight months, seven months. And she’s like, doctor, is it okay if I stop? I mean, I’m not producing.

 

00;12;05;05 – 00;12;26;26

Dr. Mona

I’m so tired. Is the baby still going to have the protective benefits? And, you know, if I’m only giving 30% breast milk or, you know, 70% formula and I say, I’m like, mom, you need to do what’s best for you. I mean, you are giving your baby nutrition of some kind, and that’s what makes me happy. The fact that you’re even giving 30% awesome, even if you give 10% or zero, whatever makes you happy.

 

00;12;26;26 – 00;12;46;17

Dr. Mona

And but if that sentiment. Right, it’s that what you just said that that guilt of, oh my gosh, is it okay if I’m only even doing this much? Is that child going to turn out to be obese or have a low IQ and, you know, be more sick? And I don’t want moms to feel that because, yeah, it’s so much stress, especially like you said in that first year of life, I am very pro breastfeeding.

 

00;12;46;17 – 00;12;59;21

Dr. Mona

And before I have Ryan, I had a misconception, which I’m going to say right now, I said that I can do it as long as I put my mind to it, I’m going to work really hard and I’m going to breastfeed my son and.

 

00;12;59;22 – 00;13;01;05

Emily Oster

Get a win, okay, I.

 

00;13;01;07 – 00;13;13;05

Dr. Mona

Win. My TV personality is going to make this happen. I will make it happen. Whatever needs to do, whatever needs to happen. And to be honest, that mentality was not going to make me successful at breastfeeding, that.

 

00;13;13;08 – 00;13;13;27

Emily Oster

It’s not helpful.

 

00;13;13;27 – 00;13;31;26

Dr. Mona

I don’t know, because I struggled. I mean, I for anyone who doesn’t know my story, I was in ICU, my son was in the ICU. I was sick and waking myself up to pump every three hours. And I was miserable. And I said I would watch those little drops of colostrum come and I would get so excited. I’d show my husband, I would show my sister.

 

00;13;32;00 – 00;13;54;23

Dr. Mona

And then finally, when I was like, slated to go back to the O.R. for a procedure after my C-section, I was like, no, I’m done. I can’t do it. And I, I look at that whole story and I talk to my husband about this. He’s like, do you ever regret not trying more? And I say, no. I’m like, I almost feel like for me to be a breastfeeding loving pediatrician who formula fed her son is what my gift is to the world.

 

00;13;54;24 – 00;14;14;29

Dr. Mona

Like what my gift is to the world to say, you know what? You can still support breastfeeding and support moms, but have formula for your own child and support when another mother wants to go that route too. And I think that’s what we need a little bit more of. You know, I love lactation consultant, but I want lactation consultants to also understand that at some point the mother may reach their limit.

 

00;14;14;29 – 00;14;32;22

Dr. Mona

And I don’t want that mother to feel that they’re not supported in that decision. I don’t want them to feel like they’re making a bad decision by ending it. And I hate using that word. I shouldn’t, but that, you know, transitioning to another way of feeding their baby. But yeah, it’s it’s so important because there’s so many different ways to feed your baby.

 

00;14;32;22 – 00;14;48;29

Dr. Mona

And you’re like, I love Ryan. I look at him and I can’t even imagine that. I worried about that. You know? It’s like he’s a thriving young boy who’s so bright and I’m like, oh, it’s just it’s I want all the moms listening who ever worry about that decision to know that they’re supported.

 

00;14;49;01 – 00;14;52;00

Emily Oster

Yeah, I totally agree with that. And I think the other, you know, I think there’s also.

 

00;14;52;00 – 00;14;53;02

Dr. Mona

A sort of flip side.

 

00;14;53;02 – 00;15;15;03

Emily Oster

Of this, which is like we kind of simultaneously tell women like, you know, in the breastfeeding is the most important thing. And then we make it like quite hard. Not just that it’s already hard to do, but it’s like, well, you know, it’s so important to do that, but don’t show me your boobs because I don’t want to see, you know, and I think part of, for me, part of what made it go much easier with my son, I mean, part of is just the second kid is easier, but part of it is I just at some point was like, you know what?

 

00;15;15;10 – 00;15;31;18

Emily Oster

Like I’m just going to I’m like, I’m not getting any nursing covers. You know, I’m just going to like, do it wherever. And it actually was much easier because some of like some of the most difficult struggles I had with my daughter was when I was trying to like, you know, be in a hot closet or something. So people didn’t see me.

 

00;15;31;18 – 00;15;49;01

Emily Oster

And, and I think that we sort of we could, we could really balance, like, simultaneously like, let’s make it possible for people to do this if it works for them and it’s what they want. And then at the same time, let’s just like make it clear that all these other options are also great and that, like, there’s a lot of great ways to do this.

 

00;15;49;01 – 00;15;56;10

Emily Oster

And we should be sort of like broadly supportive of all of them.

 

00;15;56;13 – 00;16;17;29

Dr. Mona

And that’s your follow up. Just a small dose of the real relatable and eye opening conversations we love to have here. If you smiled, nodded or had an moment, go ahead and download, follow and share this episode with a friend. Let’s grow this village together for more everyday parenting wins and real talk. Hang out with us on Instagram at thePedsDocTalkpodcast.

 

00;16;18;01 – 00;16;33;13

Dr. Mona

Want more? Dive into the full episode and more at PedsDocTalk.com. Because parenting is better with support. And remember, consistency is key. Humor is medicine and follow ups are everything. I’m Doctor Mona. See you next time for your next dose.