Infants who do not get enough iron before birth have diminished mental and psychomotor development in areas of language ability, motor functions, attention, and tractability (ability to obey rules and follow orders) at 5 years of age, concludes a study supported in part by the Agency for Healthcare Research and Quality (contract 290-92-0055). Although the exact cause-effect mechanism has not been defined, researchers have shown that prenatal iron deficiency leads to alterations in neurotransmitter or neuronal metabolism and myelin formation in the brain of experimental animals, explains Robert L. Goldenberg, M.D., of the University of Alabama at Birmingham.
Dr. Goldenberg and his colleagues from the Prevention of Low Birthweight in High-Risk and Minority Women Patient Outcomes Research Team (PORT) correlated the iron status of 278 fetuses, assessed by cord serum ferritin concentrations, with test scores of mental and psychomotor development of the same 278 children at 5 years of age. The children took six tests on intelligence, language ability, fine- and gross-motor skills, attention, and tractability. The children in the lowest cord ferritin quartile scored the worst on every test and had significantly lower scores in language ability, fine-motor skills, and tractability. There were no significant differences in scores on any test between the children in the highest ferritin quartile and children in the 2 median quartiles.
Intelligence scores in the highest quartile were slightly (but not significantly) lower than in the median quartiles. The odds ratio for having intelligence scores of less than 70 (considered mental retardation) for children in the highest quartile was 3.3, but it is not clear why. High ferritin, reflecting either excessive iron or an acute-phase reaction (usually due to infection or trauma) in intrauterine life, may be associated with poor intelligence.
Details are in "Cord serum ferritin concentrations and mental and psychomotor development of children at five years of age," by Tsunenobu Tamura, M.D., Dr. Goldenberg, Jinrong Hou, M.D., and others, in the February 2002 Journal of Pediatrics 140, pp. 165-170.