Intended for healthcare professionals

Letters When to wean

Analysis article on breast feeding was misleading

BMJ 2011; 342 doi: (Published 15 February 2011) Cite this as: BMJ 2011;342:d987
  1. Mary J Renfrew, professor of mother and infant health, and director1,
  2. William McGuire, professor of child health2,
  3. Felicia M McCormick, research fellow1
  1. 1Mother and Infant Research Unit, Department of Health Sciences, University of York, Area 4, Seebohm Rowntree Building, York YO10 5DD, UK
  2. 2Hull York Medical School, John Hughlings Jackson Building, University of York, York YO10 5DD, UK
  1. mary.renfrew{at}

Fewtrell and colleagues’ analysis article on the evidence for six months’ exclusive breast feeding1 hit the headlines—negative comment on breast feeding in professional and scientific journals usually does. It has resulted in confusion among families and health professionals internationally about the relative merits of breast feeding and formula feeding. It has put at risk years of large scale collaborative international work to promote breast feeding and support women,2 3 already a hard task in cultures that are antagonistic to breast feeding.4 5 It is important therefore to consider whether the paper that prompted this media interest offers a worthwhile contribution to knowledge.

As a review, this piece fails on all quality criteria. In an area that potentially affects the health of millions of babies and women, the principles of systematic reviewing, developed to protect professionals and the public from incomplete and biased information, have been disregarded. Two examples illustrate the consequences.

Firstly, Fewtrell and colleagues challenge the findings of the 2002 review of optimal duration of exclusive breast feeding by the World Health Organization (in fact updated in 20096). Instead they cite a Nestle supported review that says that it “found no compelling evidence to support change” from four months to around six months of exclusive breast feeding. A quick appraisal of this review shows several factual errors and misrepresentation of its conclusions in Fewtrell and colleagues’ summary.

Secondly, they list catastrophic consequences of iron deficiency as potential sequelae of exclusive breast feeding, yet the study they cite in support is not relevant. They omit to mention important related factors, including the increased bioavailablity of iron in breast milk and increased infection in infants who are not breast fed.

Why choose to examine this topic? The optimum duration of exclusive formula feeding is a more pressing public health question. International recommendations on the timing of introduction of solids are based only on evidence on exclusive breast feeding, and evidence on the health consequences of exclusive formula feeding after four months is completely lacking.

This paper has not advanced knowledge but confused and misled; it is also likely to have increased international sales of formula milk. Peer review by those with knowledge of the field should have prevented that.


Cite this as: BMJ 2011;342:d987


  • Competing interests: None declared.


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