Half-Baked Advice for Mothers

A certain amount of half-baked advice for mothers is being offered in the name of preventing childhood obesity. Two recent publications bring two examples into sharp focus: breastfeeding and Caesarean births.

In JAMA Pediatrics this week, Lisa Smithers and colleagues reviewed evidence for an effect of breastfeeding on obesity and intelligence. She notes claims for a benefit of breastfeeding in preventing obesity, and ultimately concludes that such claims are unjustified by evidence:

By properly considering all the evidence currently available, our view is that breastfeeding affects IQ but not obesity.

In the BMJ, Jan Blustein and Jianmeng Liu review the evidence for an association between caesarean birth and chronic diseases like obesity, diabetes, and asthma. They argue that these risks should be considered in guidelines for Caesarean deliveries. The trouble is that the observed risks might be coincidental or they might be effects of Caesarean births. The evidence is inconclusive.

Predictably, hundreds of headlines are warning that “Cesarean birth may raise baby’s risk of asthma, diabetes and obesity.”

Professor David Allison, an outspoken advocate for scientific rigor, comments on this question:

The observational studies show the plausibility that Caesarean delivery has particular negative long-term consequences. That said, as the authors indicate, there is an insufficient body of randomized evidence to confirm or refute any such long-term effects.

As beautifully illustrated in a cogent editorial on the analogous situation with breastfeeding, ordinary observational studies alone are not reliable indicators of causal effects. Refined forms of observational studies and whenever possible randomized controlled trials (RCTs) are needed to test for causal effects. Such randomized studies have been done for situations as challenging, sensitive, invasive, and costly as:
• The effects of rape prevention programs (link)
• Moving from a poor neighborhood (link)
• Food marketing strategies (link)
• Surgical interventions (link)
• Early childhood interventions followed into adulthood (link)
• Breastfeeding (link)

For questions as important as these, we should invest in the kind of studies which will give us answers.

Decisions about childbirth and breastfeeding are intensely personal and important. Given their importance, health professionals should be careful to stick with the facts when they help mothers making such decisions. Half-baked advice about preventing obesity has no place in this realm.

And by all means, we need definitive research to answer these questions.

Click here for the review by Smithers et al, and here for the review by Blustein and Liu.

Baking, photograph © Anne Marthe Widvey / flickr

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