Breast feeding and obesity: cross sectional study
BMJ 1999; 319 doi: https://doi.org/10.1136/bmj.319.7203.147 (Published 17 July 1999) Cite this as: BMJ 1999;319:147
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Von Kries and coworkers have shown that the prevalence of obesity in
children aged 5 and 6 is dependent on the duration of breast feeding. 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 decrease the
prevalence of obesity in childhood.
However, because the mothers´ reasons
for not initiating or stopping to breast feed were not investigated in the
respective study, we suggest that future studies attempt to co-address
this important issue.
Maternal overweight and obesity have been shown to
interfere with both the initiation and duration of breast feeding (Hilson
et al., 1997). In a study of 514 women who were followed-up for six months
after birth of their child almost one half of those women who started
breast feeding felt they did not have enough milk at some stage; 49% of
those who subsequently sought advice from a health professional were
advised to feed more often, 42% said that they had been advised to give
bottle feeds (Graffy, 1992). In this study the mothers mentioned an
inadequate milk supply as the most common reason for stopping to breast
feed.
In the light of findings indicating that energy intake and nutritive
sucking behaviour contribute significantly to measures of body weight and
composition at 1 year of age (Stunkard et al., 1999), it seems likely to
assume that the mothers of such heavier children are more likely to early
on switch to bottle feeds than mothers of less heavier children with a
lower energy intake.
Thus, in this context the recommendation to continue
breast feeding to reduce the risk of childhood obesity might very well
represent a considerable strain to both mother and child.
Graffy JP (1992) Mothers´attitudes to and experience of breast
feeding: a primary care study. Br J Gen Pract 42: 61-64
Hilson JA, Rasmussen KM, Kjolhede CL (1997) Maternal obesity and
breast-
feeding success in a rural population of white women. Am J Clin Nutr 66:
1371-1378
Stunkard AJ, Berkowitz RI, Stallings VA, Schoeller DA (1999) Energy
intake, not energy output, is a determinant of body size in infants. Am J
Clin Nutr 69: 524-30
Professor Johannes Hebebrand
Clinical Research Group,
Department of Child and Adolescent Psychiatry of the University of
Marburg,
Schützenstr. 49,
D- 35033 Marburg,
Germany
Hebebran@post.med.uni-marburg.de
Frank Geller M.Sc
Biometrician
Andreas Ziegler Ph.D
Biometrician
Institute of Medical Biometry and Epidemiology, Philipps-University
of Marburg, Bunsenstr.3, D-35033 Marburg, Germany
Competing interests: No competing interests
Editor,
Von Kries et al have suggested that the risk of obesity in
children at the time of school entry can be reduced by breast-feeding (1).
We have investigated feeding habits during infancy of 438 obese children
of the Greater Naples attending our outpatient Department during 1997
and of 714 non-obese primary school pupils observed for a child health
survey in the same area during 1995.
Obesity was defined as ideal body
weight above 120% according to Tanner; questionnaires on feeding habits
and socioeconomic characteristics were administered to the parents of
the children by trained interviewers. Exclusive breast feeding was
defined as the child being fed no food other than breast milk. Odds ratios with 95% confidence intervals were calculated and
stratified analysis was used to investigate the role of confounding.
The
mean age was 8.2 years (range 4 to 13) for obese and 8.7 (range 6 to
10) for not obese children. Obese children were less likely to have been
breast fed than controls and a dose-response effect was observed
(Table). The association was not modified after adjusting for
parental education, number of other children and birth weight. When we
stratified the data by age, the 92 obese children aged 5 and 6 were
significantly less breast fed than the 150 controls of the same age group
(odds ratio 0.43, 95% confidence intervals 0.24 to 0.77), but the 346
older obese children were not less breast fed than the 564 controls
(odds ratio 0.79, 95% confidence intervals 0.58 to 1.07).
It seems then
from our data that breast feeding can represent a protective factor
against the development of obesity among younger children, but not among
those who are older and who are more likely to be obese also during
adulthood (2).
References
1 Von Kries R, Koletzko B, Sauerwald T, von Mutius E, Barnert D,
Grunert V et al. Breast feeding and obesity: cross sectional study.
BMJ 1999; 319:147-150.
2 Whitaker RC, Wright JA, Pepe MS, Seidel KD, Dietz WH. Predicting
obesity in young adulthood from childhood and parental obesity. N
Engl J Med 1997; 337:869-73.
Table: Breast feeding among obese and non obese
children. Values are numbers (percentages)
______________________________________________
Breast feeding Obese Non-obese
(n= 438) (n= 714)
______________________________________________
Never 154(35.1) 195 (27.3)
0-90 days 147(33.6) 241 (33.7)
> 90 days 137(31.3) 278 (38.9)
______________________________________________
ever vs never breast fed: odds ratio = 0.69, 95% confidence intervals
0.53 to 0.90;
X square for trend= 9.9, p<0.01
Competing interests: ______________________________________________Breast feeding Obese Non-obese (n= 438) (n= 714)______________________________________________Never 154(35.1) 195 (27.3)0-90 days 147(33.6) 241 (33.7)> 90 days 137(31.3) 278 (38.9)______________________________________________
Cross Sectional Methodology
In the article by Kries et. al. (1999), the authors looked at the
association between breast-feeding and obesity. The study found a
significant reduction in obesity for those who breast-fed and claimed that
a 35% reduction in obesity occurs if children are breastfed for 3 to 5
months. The study presented interesting data on a simple solution to a
prevalent problem but failed to acknowledge a major limitation in study
design. The study was cross sectional in nature and therefore causal
statements can not be made. In a later meta-analysis (1), a significant,
but more modest overall effect was determined based around this research
question. This is partially due to the stronger methodology in cohort
studies used in the meta-analysis. Cross sectional studies are important
in providing direction for research but it is important to note the
limitations of the methodology in the study so clear judgments can be
made from the research.
1. S Arenz, R Rücker, B Koletzko and R von Kries. Breast-feeding and
childhood obesity—a systematic review. International Journal of Obesity
(2004) 28, 1247–1256.
Competing interests:
None declared
Competing interests: No competing interests