Arbor Clinical Nutrition Update #167
NUTRITION RESEARCH REVIEW
Study 1: Exclusive breastfeeding in developing country
Exclusive breast-feeding for 6 rather than 3 months does not produce
significant adverse effects on growth, and protects against gastroin-
testinal infection, according to a study from the former Soviet repub-
lic of Belarus.
The 6-month exclusive breastfed group had slightly slower weight and
height gain in the second three months of life, compared with the 3
month exclusive breastfed group (differences of 29gm/month and 1.1mm >
However, the 6-month group had greater length gain in the period from
6-12 months than did the 3-month group (0.9 mm/month) and a greater
head circumference at 12 months (0.19 cm).
There was also a significantly lower level of gastrointestinal infec-
tion between 3 and 6 months of age in the 6-month compared with 3-month
Reference: Am J Clin Nutr. 2003 Aug; 78(2): 291-5.
Study 2: Growth similar in a Western country
Infants who are exclusively breastfed until 6 months of age do not grow
differently to those who are only partially breastfed, according to a
new Swedish study.
There were no statistically significant differences between the exclu-
sively breastfed children and those who had been regularly receiving
formula by 16 weeks of age.
Reference: Acta Paediatr. 2003; 92(2): 145-51.
Breastfeeding well into the first year of life has undoubted health ad-
vantages for the infant.
However, one question that has been raised is whether infants exclu-
sively breastfed beyond 3 months and particularly after 6 months of age
might have lesser average energy intake and lower growth, compared to
infants receiving formula at that time (whether alongside breast milk
or instead of it). And if this is so, is it a physiological effect of
breastfeeding or a confounding effect of other variables that influence
breastfeeding choice, particularly in less well-nourished populations.
In a Danish study, for example, infants breastfed for at least 7 months
gained nearly 200 gm less weight and 7 mm less length from 5 to 10
months of age than infants who were not breastfed. On the other hand,
in a sample of Kenyan children, those breastfed for longer were found
to grow more than those breastfed for shorter periods, right up to 2
years of age.
By no means is it the case that such differences in growth, if they ex-
ist, are necessarily a problem. But many experts believe that there is
at least a need to revise the current growth chart standards to prop-
erly account for children breastfed for extended periods. The current
standards have tended to be established using infant populations where
many children were formula fed.
In interpreting any research looking at breastfed infants, it is essen-
tial to be certain about exactly what is being studied and compared.
Are we talking about exclusive breastfeeding, how much breastfeeding is
taking place in the `control' group, what effort has been made to con-
trol for the various factors (such as education, illness and poverty)
that can influence both the mother's breastfeeding choice and health
outcomes in the child? All these factors have to be looked at.
In the Swedish study (Study 2 above), for example, there was a fairly
high level of partial breastfeeding in the `control' group and the
mothers as a whole would be expected to be a fairly well nourished
group, thus making it less likely that differences in growth associated
with breastfeeding would be found.
In the study from Belarus, on the other hand, the children exclusively
breastfed for the longer period did grow a little less during the sec-
ond 3 months of life than those children exclusively breastfed for a
shorter period. However, this growth difference was largely made up
during the following 6 months, and moreover the children breastfed for
longer had less GIT infection.
The fact that the Belarus observational study was conducted within a
community based, controlled intervention trial adds to its strength,
because there was likely to be less influence of the confounding socio-
economic, educational and health influences that are so strong in rela-
tion to breastfeeding choice.
It is also interesting that the results from this Belarus study were in
accord with another trial from India that has just been published. In
the Indian study (randomised at the community level) an intervention
designed to promote extended, exclusive breastfeeding resulted not only
in greater breastfeeding but also normal growth and less diarrhoea.
Overall, these new studies are very reassuring about prolonging exclu-
sive breastfeeding beyond 3 months of age. At the same time, there
seems to be merit in efforts to revise growth standards to better align
with breastfed babies.
To send a message to AFRO-NETS, write to: firstname.lastname@example.org
To subscribe or unsubscribe, write to: email@example.com
in the body of the message type: subscribe afro-nets OR unsubscribe afro-nets
To contact a person, send a message to: firstname.lastname@example.org
Information and archives: http://www.afronets.org