Abstract Background The effect of breastfeeding on cognitive development in the child remains controversial. The commonly observed association between breastfeeding and higher intelligence quotient (IQ) scores in children may result from the numerous confounding factors in this complex relationship. The aim of this study was to examine whether breastfeeding is associated with later differences in children's cognitive and neurological development. Methods Secondary analysis from a 9‐year follow‐up study of children of 982 smokers recruited to a randomized controlled trial of anti‐smoking education in pregnancy in a maternity hospital between November 1981 and October 1982; and all ex‐smokers and a random 25% sample of non‐smokers during the same period (total 1853 women). Cognitive and neurological development of children was assessed by psychologists in schools using the British Ability Scales and Quick Neurological Screening Test (QNST). Data on breastfeeding and factors relevant to child development were drawn from interviews with mothers at home. Main outcome measures were IQ and QNST scores. Results A total of 1218 (66%) children were followed up. In total, 61.6% of children were breastfed, median duration being 12 weeks. Before adjustment, breastfeeding was significantly associated with higher total, verbal and visual IQ scores in children, and increasing duration was significantly correlated with IQ scores. Total IQ was 5.49 points higher in breastfed children ( P ≤ 0.0

between breastfeeding status and WISC IQ scores by nearly a third, but further find the relationship between breastfeeding duration and WISC IQ scores to be Discussions of race and intelligence—specifically regarding claims of differences in intelligence along racial lines—have appeared in both popular science and academic research since the modern concept of race was first introduced. With the inception of IQ testing in the early 20th century, differences in average test performance between racial groups have been observed, though these differences h Environmental factors including childhood lead exposure, low rates of breast feeding, and poor nutrition are significantly correlated with poor cognitive development and functioning. For example, childhood exposure to lead — associated with homes in poorer areas — correlates with an average IQ drop of 7 points, and iodine deficiency causes a decline, on average, of 12 IQ points. Such impairments may sometimes be permanent, but in some cases they be partially or wholly compensated for by later growth. The first two years of life are critical for malnutrition, the consequences of which are often irreversible and include poor cognitive development, educability, and future economic productivity. Mackintosh points out that, for American black people, infant mortality is about twice as high as for white people, and low birth weight is twice as prevalent. At the same time, white mothers are twice as likely to breastfeed their infants, and breastfeeding is directly correlated with IQ for low-birth-weight infants. In this way, a wide number of health-related factors which influence IQ are unequally distributed between the two groups. The Copenhagen consensus in 2004 stated that lack of both iodine and iron has been implicated in impaired brain development, and this can affect enormous numbers of people: it is estimated that one-third of the total global population is affected by iodine deficiency. In developing countries, it is estimated that 40% of children aged four and under have anaemia because of insufficient iron in their diets. Other scholars have found that simply the standard of nutrition has a significant effect on population intelligence, and that the Flynn effect may be caused by increasing nutrition standards across the world. James Flynn has himself argued against this view. Some recent research has argued that the retardation caused in brain development by infectious diseases, many of which are more prevalent in non-white populations, may be an important factor in explaining the differences in IQ between different regions of the world. The findings of this research, showing the correlation between IQ, race and infectious diseases was also shown to apply…