The disabling flaw that renders studies comparing breastfeeding to formula feeding meaningless

flaw colorful word on the wooden background

Nearly all studies on the purported benefits of breastfeeding over formula feeding are meaningless.

Why?

Because the choice of the comparison groups is beset by a disabling flaw.

Babies who were breastfed but failed to thrive must be placed in the breastfeeding group, NOT the formula group.

Nearly all breastfeeding studies compare two groups of infants, those that have been breastfed and those that have not. Babies who were breastfed but failed to thrive are inappropriately placed in the formula feeding group, instead of the breastfeeding group where they belong.

To understand why that’s a critical problem, it helps to consider another example.

Imagine we are trying to determine the risks of homebirth. We can’t simply compare death rates of babies born at home to death rates of babies born in the hospital. That would lead to an erroneous outcome since many women who develop complications during homebirth are transferred to the hospital where the baby is ultimately born.

If we looked only at place of birth at the moment of delivery, we would erroneously include the homebirth complications in the hospital group. Homebirth would end up looking much safer than it is in reality. The appropriate comparison is women who intend to give birth at home and women who intend to give birth in a hospital.

How does that apply to breastfeeding studies?

Most breastfeeding studies compare babies who are breastfed with babies who are not breastfed at a moment in time weeks or months after birth (3 months, 6 months, one year). But when we only look at breastfeeding status at a particular moment in time, babies who develop complications from breastfeeding will mistakenly end up in the formula group. The appropriate comparison is women who intend to breastfeed and women who intend to formula feed.

If we want to know the difference between babies who are breastfed and those who are formula fed, we must place the babies who failed to thrive on breastfeeding in the breastfeeding group, NOT the formula group.

Sure, successful breastfeeding might be beneficial compared to formula feeding, but that’s something entirely different than claiming that breastfeeding is better than formula feeding. The truth could be the opposite: that when compared to breastfeeding (both successful AND unsuccessful), formula feeding is not merely beneficial, it is life saving. And, therefore, many mothers who are formula feeding are doing so because of the extraordinary benefits of formula.

The bottom line?

Studies that compare breastfeeding to formula feeding but put breastfeeding failures into the formula feeding group suffer from a disabling flaw that makes their results meaningless. In other words, nearly the entire literature that claims to show that breast is best shows nothing of the kind!

  • fiftyfifty1

    This is why the Belarus PROBIT study is so important: it has an intention-to-treat study design. In other words the outcomes for all the babies in the “breastfeeding intervention” group are kept in that group, even when some of them end up getting formula.