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Breastfeeding and Autism Risk

Have researchers looked at whether breastfeeding or formula feeding affects autism risk?

This week’s “Got Questions?” answer comes from Alycia Halladay, PhD, Autism Speaks senior director of environmental and clinical sciences

The decision to breastfeed or not is a complicated and personal one. At the same time, we hear from many mothers concerned that their decision may have contributed to their child’s autism. We know that breast milk widely benefits infant health. The American Academy of Pediatrics recently reaffirmed its support of breastfeeding infants exclusively for the first six months and in combination with introduced food through the first year.

In terms of autism risk, a number of research reports have considered breastfeeding versus formula. None directly tested whether breast milk – from the breast or a bottle – reduces or increases risk for autism spectrum disorder (ASD). However, most show that children with ASD are more likely to have been either bottle fed from birth or weaned early than are comparison groups of children not affected by ASD.

So why can’t we say “formula feeding causes autism”? There are too many related variables that may be affecting risk. Studies to date have not been able to exclude these other factors. As a result, we only know that formula feeding appears to “correlate,” or coincide, with increased risk of autism. But we don’t know that it causes autism or directly increases risk. For example, studies have associated a mother’s socioeconomic status and educational level to the likelihood that she breastfeeds. These differences may also affect the risk that her child develops autism.

In addition, the studies conducted so far have involved relatively small groups of children and families in communities with distinct breastfeeding patterns and cultural norms. Here again, there may well be other, unidentified risk factors at play. These factors are associated with particular groups that tend to breastfeed, but they don’t directly involve breastfeeding. For example, mothers who breastfeed may, as a group, tend to eat differently than mothers who don’t breastfeed. The diets of their infants may differ as well. Also, studies so far have not taken into account the gestational age of the infant at birth. This, too, can affect both the likelihood of breastfeeding and – independently – the risk that an infant will go on to develop autism.

While we can’t say whether breastfeeding or formula feeding is related to autism risk, we know there are many good reasons to encourage breastfeeding whenever possible. Clearly, prenatal and early postnatal nutrition is incredibly important for the health and welfare of children. This includes the nutrition a child receives through prenatal vitamins and the mother’s diet during pregnancy, breast milk and colostrum, and early diet (including postnatal vitamins if recommended by a doctor).

Got more questions? Please send them to You can read all our “Got Questions?” blogs here.

The Autism Speaks blog features opinions from people throughout the autism community. Each blog represents the point of view of the author and does not necessarily reflect Autism Speaks' beliefs or point of view.