Birth weight of children is inversely associated with the risk of hospitalisation for an infectious disease. Infants born prematurely and those whose growth is restricted during pregnancy have an immature immune function. Studies have shown that these low birth weight children have higher mortality rates from infection. However, there is less evidence of a relationship between birth weight and rates of illness from infection. Researchers from the Statens Serum Institute, Copenhagen, Denmark, examined the relationship between birth weight and hospitalisation due to an infectious disease in 2 million children from 1977 through 2004. They analysed information on birth weight and hospital admissions for an infectious disease. The researchers observed an inverse association between birth weight and the risk of infectious disease hospitalisations. The risk of hospitalisation between birth and the age of 14 years increased by 9 percent for each half Kg reduction in birth weight. The risk peaked in infancy and persisted until the children were10 years old. This effect of low birth weight was seen in all infants irrespective of whether they were preterm or full-term infants. The association between birth weight and infectious disease in infancy is biologically plausible as a result of a depressed immune system. However, the explanation for why the association persists into childhood requires further studies.
American Journal of Epidemiology,
April 2007