Predicting iron status in low birthweight infants

OBJECTIVE: To determine the iron status of a selected group of low birthweight infants at approximately 9 months of age, and examine the feasibility of predicting iron status by examining the history of supplementary iron intake. METHODS: All live low birthweight infants recorded in the Dunedin Hospital Queen Mary Maternity Unit birth register who reached 9 months of age between November 1995 and September 1996 were eligible to participate. Infants were categorized into 'high' or 'low' iron intake groups depending on their consumption of infant formula or medicinal iron for one month prior to the study, and their iron status compared. RESULTS: Eighty-one infants of 73 mothers, with an average age of 10 months (range 8-13 months), participated. Thirty-three per cent (n = 27) were iron deficient: 19% (n = 15) had latent iron deficiency and 15% (n = 12) had iron deficiency anaemia. Those with a 'low' iron intake were 13-fold more likely to be iron deficient than infants with a 'high' iron intake (95% confidence interval: 4.4-41.5). Screening for iron deficiency using categories based on supplementary iron intake had a positive predictive value of 66% and a negative predictive value of 88%. CONCLUSIONS: The risk of iron deficiency was considerably greater for infants who had not received supplementary iron daily over the course of the previous month. Current preventative methods for avoiding poor iron status in this group of high risk infants are not effective. Screening for iron deficiency in low birthweight infants on the basis of iron intake from infant formula or medicinal iron provides a useful method for identifying infants whose iron status should be investigated.