Breastfeeding and mommy wars

Last week, a paper came out in a relatively obscure journal and got a lot of attention (or at least got its own #slatepitches headline). A sociologist at Ohio State published a study saying that the positive effects of breastfeeding essentially disappear if you look at within-sibling differences. That is to say if you compare two siblings from the same parents, one of whom was breastfed and one of whom wasn’t, there isn’t much in the way of statistically significant differences in their educational achievement, health status, or intelligence as measured by standardized tests.

In many ways, this isn’t surprising. We already know that the vast majority of our later life outcomes are determined by our parents’ incomes and education levels, where we grow up, how many words are said to us before we can even talk, and the myriad investments our parents make in our parents’ health. That breastfeeding doesn’t make a very big difference among siblings shouldn’t surprise us.

Perhaps even more important though, and this is really the kicker when trying to identify the effects of early childhood interventions, is that we don’t know what else the parents did differently for these two children. Given what we know about mothers who breastfeed—they tend to be wealthier and more educated, they get more assistance with breastfeeding education, they tend to have more flexible jobs that allow them to breastfeed for longer, or are staying at home with their kids, they’ve been told for years, etc.—we also expect them to be conscientious if they for some reason are not breastfeeding one of their children. Colen’s analysis can only control for time-invariant, mother-specific characteristics. An important omission is that she can’t control for mothers who supplement bottle-feeding with additional doctor’s visits, vitamins, extra care, more time spent together, or any other activity or characteristic that would act as a complement to breastfeeding. It ignores anything that might cancel out the fact the child isn’t getting the extra nutrients and other stuff that we ascribe to breastfeeding.

This omission is only important if it’s correlated with breastfeeding, and in all likelihood, it is. If you thought your child was missing out by not being breastfed, mothers with the ability to might try to compensate by increasing other investments.

It’s also worth noting that there are other studies using the same methodology that do find within-family effects for breastfeeding. This one, for instance, by Rees and Sabia.

Ultimately Colen wants to use the results to push for more family-friendly social policy, like increased maternity leave and more. But this is not the last word on breastfeeding. One momy blogger called it a “suspect methodology.” It’s not, it’s a perfectly valid methodology, but we need to be careful about what it’s actually showing.


Rees, Danial and Joseph Sabia. 2009. “The Effect of Breastfeeding on Educational Attainment: Evidence from Sibling Data.” University of Colorado at Denver Working Paper 09-03.

Colen, Cynthia and DM Ramey. 2014. “Is Breast Truly Best?:Estimating the effects of breastfeeding on long-term child health in the United States using sibling comparisons.”Social Science and Medicine.

Hart, B. & Risley, T.R. “The Early Catastrophe” (2004). Education Review, 77 (1), 100-118.


The costs of breastfeeding

When I started writing my final dissertation chapter, I chose to examine two investments in children–breastfeeding and taking children to the doctor–which I assumed to have different cost structures. The idea was that breastfeeding would be a time-intensive investment, while taking children to the doctor would be a monetarily intensive investment.

Further research showed that this dichotomy was clearly false. In order to breastfeed, one has to consume more calories, sleep less, and generally be available more. While I generally only cite the additional caloric cost in my presentation, new research highlights other costs of breastfeeding, which manifest themselves in wage penalties that accrue over time. From the Motherlode blog at the NYT:

Now researchers have zeroed in on an economic cost of following the pediatrician’s advice: women who breast-feed for six months or more suffer more severe and more prolonged earnings losses than mothers who breastfeed for a shorter amount of time, or not at all,” writes Tom Jacobs for Miller-McCune.

While mothers may not have to physically outlay cash in order to breastfeed, there are definitely significant costs associated with it. If the consensus is that breastfeeding is a desirable and healthy behavior, we have to make policies to support it.

Related (from Irrational Tonics and elsewhere):

  1. Breastfeeding, formula, and perception
  2. Support for breastfeeding by Tangerine and Cinnamon
  3. My quick response to Tangerine and Cinnamon post above
  4. My paper on Health Investments in Children: healthinvestFF_071911

Breastfeeding Follow-up

After Saturday’s post about breastfeeding, Katina sent me a link to a recent blog post on the history of marketing formula and some recent legal changes, which I believe are for South Africa, concerning how formula can be marketed. It’s a bit long, but it is an interesting read. In particular, Sarah Emily’s post echoes the story I was told on Saturday:

This isn’t to suggest that women should have their choices about how they feed their babies curtailed – or that it’s only advertising which causes women to choose to use baby formula. Far from it. The problem, though, is that, particularly in poor nations, advertising or other promotional methods encourage breastfeeding mothers to switch to baby formula when it’s unlikely that they’ll be able to afford to buy more formula, and where they may dilute formula with too much water to make it go further. This water may not be clean, and it’s difficult to keep bottles and teats sterile without electricity or plumbing.

So, not only is the nutritional value of the formula decreased through dilution, but the risk of water-borne diseases is elevated.

During the question and answer session following my talk on Saturday, many women expressed concern at the very low average durations of breastfeeding in my sample, about 3 and a half months. Some people wanted to say this was so different than the norm in the rest of the world, but Sarah Emily suggests it’s not:

The cause for these new regulations and other measures introduced internationally to encourage mothers to breastfeed for the first six months of life, is a concern that rates of breastfeeding remain low in comparison to what they were during the early twentieth century. For all the good that the Code and other laws have done, it remains the exception, rather than the rule, for women to breastfeed for such an extended period of time.

She also has a great old advertisement. My only caveat to add would be that while supporting breastfeeding as a healthy choice for mothers and babies is important, it’s also critical that we not demonize women who simply cannot breastfeed. Supplying those women with formula and reducing the stigma there is important, just as it is important to create more accepting spaces for mothers to breastfeed their children.

How to look rich by not breastfeeding

Almost every time that I’ve presented one of my dissertation papers, someone comes up to me to tell me about some experience they have had that is relevant to my paper. Often, they’re not happy. My paper on parental relationship quality and reading to children tends to really rile up single mothers, all of whom want to tell me how they managed to be good parents despite having unhappy marriages. Mostly, I reiterate how these are average and then just smile and thank them for their input.

Occasionally, though, someone tells me something inspiring, or sad, that really touches me. A student came to tell me about her own experiences with a violent relationship after I presented some of my research, and many others have told me stories about parenting.

Today, I presented the second chapter of my dissertation at the Central Pennsylvania Consortium’s annual Women, Gender, and Sexuality conference. That’s a mouthful, no? My second paper explores the extent to which promises of financial support given to single mothers by the fathers of their children have an influence on financially-constrained investments in children as the child gets older.

As we all finished, a woman who works at the College came up to tell me her story of growing up in Jamaica. She told me how formula was marketed to upper class mothers and so became a sign of wealth. And conversely, breastfeeding became a sign of poverty. Many mothers with few resources, she said, wanted to appear as though they were giving their children formula–the marketed as healthier option as well as the option that signaled ability to pay. Consequently, these mothers would use their limited resources to buy formula, but then would water it down in order to have more opportunities to show they were feeding their children with formula.

It broke my heart to hear it, but it also showcases a rather important problem that economists have. When we rely on survey data and on averages, all of these women would say that they used formula, but likely the nutritional outcomes for their children would be much different. So, not only is there a reporting problem whereby poor mothers might understate for how long and whether they breastfed, but the quality of the alternative has much more variability in nutritional value.

Outside of the measuring problem, I don’t think we’re all that good at identifying these types of what we would call irrational behavior. Without having interviewed women in depth or been there to witness this behavior, we likely would not include it in our analysis, leading to biased estimates.

%d bloggers like this: