Cord Serum Ferritin Concentrations and Mental and Psychomotor Development of Children at Five Years of Age

Abstract

There is clear evidence that iron deficiency in early life can lead to enduring delay in mental and psychomotor development. Trials of iron supplementation have, however, failed to consistently demonstrate benefit. The authors assessed fetal iron status by determining the umbilical-cord serum ferritin concentration by radioimmunoassay in 278 children and related the findings to full-scale intelligence quotient (FSIQ), language ability, fine and gross motor skills, attention, and tractability at age 5 years. Participants took part in a study designed to identify risk factors for small-for-gestational-age (SGA) infants. Mothers completed the Home Screening Questionnaire, a measure of the home environment for children, as well as the Peabody Picture Vocabulary Test, a measure of cognitive function. In addition to the FSIQ, children completed the Test for Auditory Comprehension of Language (TACL), the Peabody Developmental Motor Scales, and the Yale Children's Inventory for attention and tractability (the ability to obey rules of decorum). The mothers were predominantly African-American and had scores typical of a resource-poor inner city population. The prevalence of preterm birth before 37 weeks' gestation was 13%, and that of SGA infants was 22%. Birth weights were lower for those in the lowest quartile of serum ferritin. After adjusting for gender, birth weight, and smoking, cord ferritin levels correlated significantly but weakly with maternal serum ferritin levels at 36 weeks' gestation. Children in the lowest quartile of cord blood ferritin scored the lowest in all tests, and had significantly lower scores on the TACL and the test of fine motor function than did those in the two median quartiles. There were no such differences in FSIQ or gross motor function scores. In no respect did the children in the highest ferritin quartile differ from those in the median quartiles. Analyzing test scores below the 15th percentile, the chance of a low score on any of the tests was increased by at least 60% for children in the lowest ferritin quartile. Children in the highest ferritin quartile were more than 3 times as likely as those in the two median quartiles to have a FSIQ score lower than 70 (the 15th percentile cutoff score). These findings suggest that poor iron status at birth is associated with impaired performance on mental and psychomotor evaluation at age 5 years. The finding that high ferritin levels correlate with low FSIQ scores remains unexplained.