Intended for healthcare professionals

Rapid response to:


Six months of exclusive breast feeding: how good is the evidence?

BMJ 2011; 342 doi: (Published 13 January 2011) Cite this as: BMJ 2011;342:c5955

Rapid Response:

Misleading opinion

The 'Comment' paper by Fewtrell et al in which questions are raised
about policy recommendations on the duration of exclusive breastfeeding
has, not surprisingly, hit the national and international headlines.

Negative comment on breastfeeding in professional and scientific journals
usually does, and widespread interest was predictable. This coverage has
resulted in confusion among families and health professionals, not just
about the health outcomes related to the duration of exclusive
breastfeeding, but about the nutritional adequacy of breastfeeding at all
after four months of age. In the past decade or so there have been
considerable advances in developing evidence-based policy on breastfeeding
across countries and across successive governments. The evidence base for
such policy has derived from thoughtful, careful scientific advances (1,2)
high quality systematic reviews on health outcomes (3,4) and good quality
evidence and reviews on effective strategies to enable women to breastfeed
(5,6,7). Such positive developments have been effected by collaborations
between researchers, policy makers, and the health professionals and
voluntary sector organisations who understand just how hard it is for
women to breastfeed in a culture that is antagonistic to breastfeeding
(8,9,10). In speculating about the nutritional adequacy and even safety of
delaying the introduction of solid foods to breastfed infants until about
six months, this paper has put this large-scale collaborative work at risk
and undermined confidence in breastfeeding.

It is important therefore to consider whether this paper offers a
worthwhile contribution to knowledge to compensate for this risk.
Although published as a Comment, the front page of the BMJ website
indicates that this paper 'reviews the evidence'. Judged as a review,
this piece fails on all quality criteria (11). No methodological details
such as a search strategy or inclusion/exclusion criteria are described to
demonstrate that bias was avoided in the selection of studies. There is no
critique of included studies, which would have identified that some of
those referred to are very small or only examine specific at-risk groups,
or do not relate to infant feeding at all (12,13); and it would have
distinguished between research studies, reviews, and opinion and
speculative articles. In other words, the principles of systematic
reviewing, developed to protect professionals and the public from
incomplete and biased information, have been disregarded. Two examples
illustrate the problems that result. Fewtrell et al challenge the findings
of the 2002 WHO review of optimal duration of exclusive breastfeeding
(14); these authors updated their Cochrane Review of this topic in 2006
(15). In support of their challenge they cite a review on the age of
introduction of complementary foods to the healthy full-term infant (16),
indicating that it included 33 studies and 'found no compelling evidence
to support change' from four months to around six months of exclusive
breastfeeding. A quick appraisal of this Nestle-supported review shows
that the 33 included papers derived from 25 studies; that studies included
both formula and breastfed babies; that those studies whose authors
concluded that delayed introduction of complementary foods to around six
months was appropriate were of relatively higher quality than those that
supported earlier weaning; and that the authors of this review in fact
state that 'there is no clear evidence to either support or refute a
change to the current recommendations'. The second example is of
particular concern. Fewtrell et al list possible consequences of iron
deficiency in their Box 2; the list includes catastrophic outcomes that
any parent would try to avoid including 'irreversible adverse mental,
motor, and psychosocial outcomes'; yet the evidence cited by these authors
in support of breastfed infants being deficient in iron comes from a US
study where the number of babies exclusively breastfed is very small, and
in which such serious iron deficiency was not measured (17). Fewtrell et
al omit to mention the well-evidenced, though often forgotten, increased
bioavailablity of iron in breastmilk (18). They also do not mention the
findings of a large RCT that demonstrated a significant decrease in IQ and
other measures of cognitive function related to formula feeding (19). A
reappraisal of the evidence may be timely, as Fewtrell et al suggest, but
their paper does not achieve this aim.

Researchers have limited time in which to write papers that will not
enhance their Research Excellence Framework profile (though such papers
will increase their citation count). Why choose to examine a topic that
is not a public health priority in a country where fewer than 1% of babies
are breastfeed exclusively at six months (20)? In regard to the timing of
the introduction of solid foods, the more pressing public health question
relates to the duration of exclusive formula feeding, which affects very
large numbers of babies in the UK and globally, yet lacks an evidence base
and has not been subjected to systematic review. WHO recommendations
refer only to breastfeeding (21), and the more recent EFSA scientific
opinion (22) also only examined evidence related to breastfeeding.
Studies and reviews of the adequacy and safety of exclusive formula
feeding should include assessment of the nutritional adequacy of a class
of products that is accepted as being of lower quality than breastfeeding,
infection and contamination risks in use of these products compared with
breastfeeding, and the risk of allergy and intolerance resulting from use
of products that include a range of non-human ingredients. Assessment of
the impact of not breastfeeding, exclusively or at all, on women's health
and wellbeing is also important (23) an aspect not addressed by Fewtrell
et al.

Sadly, this paper has not advanced knowledge, but rather confused and
misled. It has thereby resulted in national and international media
coverage that is likely to increase the sales of formula. Peer review by
those with knowledge of the field should have prevented that.

1. Howie PW, Forsyth JS, Ogston SA, Clark A, Florey CD. Protective
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2. Quigley MA, Kelly YJ, Sacker A. Breastfeeding and hospitalization for
diarrheal and respiratory infection in the United Kingdom Millennium
Cohort Study. Pediatrics. 2007;119(4):e837.

3. Ip S et al. Breastfeeding and maternal and infant health outcomes in
developed countries. Evidence Report/Technology Assessment No 153.
Rockville, Maryland: Agency for Healthcare Research and Quality; 2007.

4. Collaborative Group on Hormonal Factors in Breast Cancer. Breast cancer
and breastfeeding: collaborative reanalysis of individual data from 47
epidemiological studies in 30 countries, including 50302 women with breast
cancer and 96973 women without the disease. Lancet. 2002;Jul 20, 360:187-

5. Britton C, McCormick FM, Renfrew MJ, Wade A, King SE. Support for
breastfeeding mothers. Cochrane Database of Systematic Reviews 2007, Issue
1. Art. No.: CD001141. DOI: 10.1002/14651858.CD001141.pub3

6. Cattaneo, A. Breastfeeding in Europe: a blueprint for action. Journal
of Public Health, 2005; 13, 89-96.

7. National Institute for Health and Clinical Excellence Improving the
nutrition of pregnant and breastfeeding mothers and children in low-income
households. NICE Public Health Guidance, 11. 2008. London, NICE:

8. Henderson, L., Kitzinger, J. & Green, J. Representing infant
feeding: content analysis of British media portrayals of bottle feeding
and breast feeding. BMJ, 2008; 321, 1196-1198.

9. Dyson L, McMillan B, Renfrew MJ, Green, JM, Woolridge MW. Factors
influencing the infant feeding decision for socioeconomically deprived
pregnant teenagers: the moral dimension. Birth 2010. 37: 147-149

10. Renfrew MJ, Hall D. Enabling women to breastfeed. BMJ 2008;337:a1570,
doi: 10.1136/bmj.a1570

11. Centre for Reviews and Dissemination CRD's guidance for undertaking
reviews in healthcare. 2009. CRD, University of York.

12. Lozoff B, Jimenez E, Hagen J, Mollen E, Wolf AW. Poorer behavioural
and developmental outcome more than 10 years after treatment for iron
deficiency in infancy. Pediatrics 2000;105:E51.

13. Halterman JS, Kaczorowski JM, Aligne CA, Auinger P, Szilagyi PG. Iron
deficiency and cognitive achievement among school-aged children and
adolescents in the United States. Pediatrics 2001;107:1381-6.

14. Kramer MS, Kakuma R. The optimal duration of exclusive breastfeeding:
a systematic review. World Health Organization, 2002.

15. Kramer MS, Kakuma R. Optimal duration of exclusive breastfeeding.
Cochrane Database of Systematic Reviews 2002, Issue 1. Art. No.: CD003517.
DOI: 10.1002/14651858.CD003517. Last assessed as up to date Dec 30, 2006.

16. Lanigan JA, Bishop J, Kimber AC, Morgan J. Systematic review
concerning the age of introduction of complementary foods to the healthy
full-term infant. Eur J Clin Nutr 2001;55:309-20

17. Chantry CJ, Howard CR, Auinger P. Full breastfeeding duration and risk
for iron deficiency in U.S. infants. Breastfeed Med 2007;2:63-73.

18. Saarinen UM, Siimes MA, Dallman PR. Iron absorption in infants: high
bioavailability of breast milk iron as indicated by the extrinsic tag
method of iron absorption and by the concentration of serum ferritin. J
Pediatr 1977;91:36-9

19. Kramer MS, Aboud F, Mironova E, Vanilovich I, Platt RW, Matush L, et
al. Breastfeeding and child cognitive development: new evidence from a
large randomized trial. Archives of General Psychiatry. 2008;65(5):578.

20. Bolling, K., Grant, C. & Hamlyn, B. Infant Feeding Survey 2005.
2007; The Information Centre for Health and Social Care: London.

21. World Health Organization. 55th World Health Assembly. Infant and
Young Child Nutrition. World Health Organization, 2002 (WHA55.25).

22. European Food Safety Authority (EFSA), EFSA Panel on Dietetic
Products, Nutrition and Allergies (NDA). Scientific opinion on the
appropriate age for introduction of complementary feeding of infants. EFSA
Journal 2009;7:1423.

23. Collaborative Group ibid

Competing interests: No competing interests

19 January 2011
Mary J Renfrew
Professor of Mother and Infant Health and Director, Mother and Infant Research Unit
William McGuire, Felicia McCormick
Department of Health Sciences, University of York, UK