Re Rachael Hamlet's request for citations: In the most well-known of his papers on this subject, Lucas et al (Lancet 339:261-264, 1992) cite several studies that related breastfeeding to IQ based on earlier periods when the correlation was the opposite (wealthier families were the ones that bottle fed). They mention that one of these studies from 1946 seems to provide this kind of support--improved IQ in spite of lower SES for the breast-fed group. I have ordered one of the really old studies (1929) to see what they came up with. Lucas et al do a good job of controlling for SES and mother's education but did not measure mother's IQ, known to be a big factor associated with baby's IQ (ie genetic). Wright and Deary criticize them for this (Lancet 339:612-613, 1992) but Lucas and Cole do a good job on the second page of that reference in answering this criticism. Lucas et all were studying premature babies who received breast or regular (not special premature) formula by tube. Thus they were measuring an effect of breast milk, not breastfeeding. This effect might not hold for full term babies, since prematures might be more sensitive, especially in their ability to synthesize long chain fatty acids in the presence of inadequate DHA or an imbalance in fatty acids. Lucas, et al also found that babies of mothers who wanted to breast feed but could not did no better than the ones who never intended to breast feed, supporting the hypothesis that it was an effect of breast milk, not a bias caused by the fact that a different type of mother wants to breast feed. Another group found that differences were due to breastfeeding, not breast milk (Doyle et al, Breastfeeding and intelligence, Lancet 339:744-5, 1992). Still others (Jacobson and Jacobson, Lancet 339:926, 1992) found that, while SES and maternal education did not "wipe out" the effects of breastfeeding, maternal IQ and a measure of parenting skills did. Later Lucas et al (Arch of Dis in Child 70:F141-F146, 1994) found that breast milk worked just as well as special preterm formula, even though the breast milk seemed to be deficient in several nutrients. They write that this adds "significant support to the view that breast milk promotes neurodevelopment." Ted Greiner, PhD Senior Lecturer in International Nutrition Uppsala University 75185 Uppsala Sweden phone +46 - 18 511598 fax +46 - 18 515380 e-mail [log in to unmask]