Melissa,
No one said that IQ scores are entirely due to infant feeding method.  IQ's
are multifactorial: genetics, environment and nutrition all contribute.  An
individual's IQ is meaningless in this context, it is the population figures
that show the differences between abm fed and hm fed infants.  In the best
studies, the populations were matched for socioeconomic status, education of
the parents, and as many other potential confounders as possible, then the
scores of the children are compared.  Almost all studies have found that there
is a cognitive advantage to being bf- better motor development, higher IQ,
higher scores on the Bailey Scales of Infant Development.  The only way to
determine the affect on an individual is to bf one identical twin and abm feed
the other at the breast, keeping all other aspects of the environment
identical.
        Lucas tried to compensate for all these confounders in his IQ study by
taking preterm infants whose mothers did not ever intend to bf them and
randomizing them into 3 groups, one got standard abm, one got the experimental
preterm abm, the third got some donor term "drip milk"- the lowest quality
human milk possible - the milk that drips into a breast shell while the mother
nurses her own infant on the contralateral breast.  The children who were tube
fed this drip milk had an IQ 8-10 points higher than those who were
exclusively standard abm fed.  preterm abm came out intermediate.  There has
yet been no study to do this same thing with higher quality pumped preterm
ebm, as no abm manufacturer would fund it, and most mothers at Lucas' hospital
now provide their own milk for their preterm infants since the study was
publicized.
Catherine Watson Genna, IBCLC  NYC  [log in to unmask]