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Letters

Breast feeding and obesity

BMJ 1999; 319 doi: https://doi.org/10.1136/bmj.319.7224.1576 (Published 11 December 1999) Cite this as: BMJ 1999;319:1576

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Relation may be accounted for by social factors

  1. Michael Wadsworth, director (m.wadsworth{at}ucl.ac.uk),
  2. Sarah Marshall, research assistant,
  3. Rebecca Hardy, scientific staff,
  4. Alison Paul, scientific staff
  1. MRC National Survey of Health and Development, University College London Medical School, Department of Epidemiology and Public Health, London WC1E 6BT
  2. MRC Human Nutrition Research Resource Centre, Cambridge CB4 1XJ
  3. Clinical Research Group, Department of Child and Adolescent Psychiatry, University of Marburg, Schützenstrasse 49, D-35033 Marburg, Germany

    EDITOR—In their paper on breast feeding and obesity von Kries et al report that, in a large sample of children (n=13 345) who were aged 6 in 1997, the lowest prevalence of overweight and obesity at that age was in those who had been breast fed for longest.1 By contrast, analysing data from our national longitudinal study of children born in 1946 (n=3731)2 in a comparable way, we found no significant relation of breast feeding with overweight or obesity at age 6 and a suggestion that the lowest prevalence of overweight and obesity at that age was associated with the shortest period of breast feeding (table).

    Duration of breast feeding and prevalence of being overweight* or obese† among 6 year olds living in United Kingdom in 1952, with adjusted odds ratios for independent risk factors associated with being overweight or obese in logistic model for 3550 children aged 6 in United Kingdom in 1952

    View this table:

    These findings lead us to question von Kries et al's conclusion that childhood overweight and obesity are associated with the composition of breast milk, as does our biologically implausible finding that the greatest risk of overweight or obesity was in those children who were breast fed for longest and those who were never breast fed (table).

    It seems likely that the difference in findings between our study and that of von Kries et al, and their finding of a relation between breast feeding and overweight and obesity, may both be accounted for by social factors associated with breast feeding. In Britain the prevalence of breast feeding has changed greatly over the past 60 years and has changed within classes.35 Breast feeding today is more likely to be a matter of choice, which itself would be distributed unevenly across such social factors as class and maternal occupation.

    References

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    Prolonging breast feeding to reduce obesity may be a burden

    1. Johannes Hebebrand, professor
    1. MRC National Survey of Health and Development, University College London Medical School, Department of Epidemiology and Public Health, London WC1E 6BT
    2. MRC Human Nutrition Research Resource Centre, Cambridge CB4 1XJ
    3. Clinical Research Group, Department of Child and Adolescent Psychiatry, University of Marburg, Schützenstrasse 49, D-35033 Marburg, Germany

      EDITOR—Von Kries et al have shown that the prevalence of obesity in children aged 5 and 6 is dependent on the duration of breast feeding.1 A clear dose-response effect was observed even after adjustment for potential confounding factors. The authors concluded that in industrialised countries prolonged breast feeding may help reduce the prevalence of obesity in childhood. However, future studies should attempt to address the issue of why mothers do not start breast feeding or why they discontinue it, as these issues were not addressed by von Kries et al.

      If a mother is overweight or obese this may interfere with both the initiation and duration of breast feeding.2 In a study of 514 women who were followed up for six months after the birth of their child, almost half of the women who started breast feeding felt at some stage that they did not have enough milk; 49% of those who subsequently sought advice from a health professional were advised to feed more often, and 42% said that they had been advised to bottle feed.3 An inadequate supply of breast milk was the most common reason given by mothers for discontinuing breast feeding.

      In the light of findings that indicate that energy intake and nutritive sucking behaviour contribute significantly to measures of body weight and composition at 1 year of age,4 it seems likely that the mothers of heavier children are more likely to switch to bottle feeding earlier than mothers of less heavy children who have a lower energy intake. Thus, the recommendation that prolonging breast feeding might reduce the risk of obesity in childhood might put a considerable strain on both mother and child.

      References

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