Research in context
Evidence before this study
Substantial data exist describing the increased risk of neonatal infection in infants born preterm or of low birthweight, or both, especially in infants who are very preterm or of very low birthweight. But whether infection-related morbidity is increased in childhood and adolescence, especially in those born late preterm (weeksdays: 34–36+6 weeks gestational age), early term (37 weeks+0–38 weeks+6 gestational age), or with a near-normal birthweight (2500–3000 g) is unknown. We searched PubMed on Feb 1, 2016, for English-language articles with the terms “child” AND “infection” AND “hospitalisation” AND (gestational age OR birthweight OR birth length). We identified 70 articles, 30 of which we considered relevant to the hypotheses. Of these, 20 related specifically to bronchiolitis, respiratory syncytial virus, or infection of the lower respiratory tract, and two related to gastroenteritis. Findings from all studies showed that infants of low birthweight and gestational age had an increased risk of being admitted to hospital with these infections. Most remaining studies adjusted for birthweight and gestational age in analyses of other infectious exposures. Findings from only one study from 2007 reported overall infection-related admissions to hospital in childhood from population-based Danish data. The investigators of this study reported a 9% increased rate of admission to hospital for each 500 g reduction in birthweight that persisted until age 10 years. No population-based data analyse gestational age or birth length with detailed data for late preterm or early-term infants.
Added value of this study
Findings from our analysis of 30 years of total population data from Western Australia showed that reduced gestational age, birthweight, and birth length were associated with an increased risk of being admitted to hospital with an infection from birth-related hospital discharge until age 18 years. The increased risk was noted in all clinical categories of infection and for all suboptimum birth variables, including those born late preterm, early term, and with near-normal birthweight and length.
Implications of all the available evidence
A substantial and previously unrecognised proportion of children and adolescents who were born with reduced gestational age, birthweight, or birth length are at increased risk of severe infection. Further studies should investigate whether other populations have similar findings. The policy implications of these results are substantial, in terms of optimising pregnancy outcomes and preventing infection in this population. These actions would be especially relevant in resource-limited settings where suboptimum intrauterine growth and moderate prematurity are common.