What if higher socioeconomic status CAUSES breastfeeding?

Countless studies have demonstrated a high correlation between breastfeeding and all sorts of desirable health and economic outcomes from reduced infant mortality to reduced obesity, from higher IQ to higher educational achievement. That’s led breastfeeding researchers to erroneously conclude that breastfeeding CAUSES improved outcomes.

In fact nearly all studies attributing benefits to breastfeeding are riddled with what is known as confounding variables. A confounding variable is a third phenomenon that influences both of the other two.

But there’s another serious problem that afflicts nearly all breastfeeding studies and that is the possibility of REVERSE causation. Just because two variables X and Y are closely associated even after being corrected for confounding variables does NOT mean that X causes Y. It is possible that Y causes X.

For example, imagine we did a study of substance abuse and mental health disorders and found that adolescent drugs abuse is highly correlated with mental health disorders. Should we conclude that substance abuse causes mental health disorders? Of course not. It is well known that adolescents with mental health issues abuse drugs in an effort to self-medicate. Substance abuse does not cause mental health disorders; mental health disorders cause substance abuse.

What does that mean about breastfeeding? While breastfeeding seems to cause various health and economic benefits, we may have the relationship precisely backward. Instead of breastfeeding causing benefits, it is entirely possible that the benefits “cause” breastfeeding.

How can that be? It is well known that breastfeeding is socially patterned. The value ascribed to breastfeeding is determined by income, education, ethnicity and place of residence among other things. Moreover, the ability to maintain a breastfeeding relationship depends on the availability of partner support, household wealth and maternity leave that also depend on income, education, ethnicity and place of residence.

It isn’t merely that these factors are confounding variables, though they are. It’s that higher socioeconomic status leads to strong social pressure to breastfeed and strong social stigma toward bottle feeding. In other words, breastfeeding doesn’t cause higher socioeconomic status; higher socioeconomic status causes breastfeeding and then the offspring inherent all the benefits of having higher socioeconomic status.

The distinction could not be more critical. The US has been spending countless millions each year under the mistaken impression that breastfeeding causes better outcomes yet the return on investment has been basically zero. Though breastfeeding rates have skyrocketed, the predicted decreases in infant mortality, severe morbidity and healthcare expenditures simply haven’t materialized. That’s just what you’d expect if we’ve fallen into the mistake of reverse causation.

It’s long past time to take those countless millions away from promoting breastfeeding and use them to directly improve the socioeconomic status of those who are disadvantaged:

Instead of spending millions on lactation consultants, spend it on primary school teachers, pediatricians for underserved areas and maternity leave for everyone.

Instead of spending millions on breastfeeding promotion, spend it on cleaning up pollution and reducing crime in disadvantaged areas.

And while we’re at it we could spend money making college education — a virtual prerequisite for socioeconomic success — more affordable for those with low incomes.

If we want to improve both health and economic outcomes for babies we should stop wasting money on breastfeeding. Breastfeeding doesn’t cause those health and intellectual benefits for which is has been touted; those health and intellectual benefits cause breastfeeding.