Gestational age, birth weight, and risk for injuries in childhood.

BACKGROUND

Some children experience more injuries than others due to personal or environmental risk factors, or to chance. Most injury studies have focused on proximal causes; few have examined the role of neonatal characteristics such as birth weight and gestational age.

METHODS

We carried out a population-based cohort study of 1,524,114 singletons born in Denmark between 1 January 1978 and 31 December 2004. We obtained information on gestational age, birth weight, and injury from the Danish Medical Birth Registry and the National Hospital Register. We followed participants up to age 29 years and estimated the incidence rate ratio (IRR) of hospitalization for injury, using Poisson regression models.

RESULTS

The risk of injury throughout childhood (mainly before 12 years of age) increased with decreasing gestational age and birth weight. The IRR of injury in the first 12 years of life was 4.2 (95% CI = 3.5-5.1), 2.3 (2.0-2.5), and 1.5 (1.3-1.6), respectively, for children born at gestational weeks 20-32, 33-36, and 37-38, compared with those born at gestational weeks 39-41. The IRR was 4.0 (3.4-4.6), 2.5 (2.1-2.8), and 1.4 (1.3-1.6) for children with a birth weight less than 2000 g, 2000-2499 g, and 2500-2999 g, compared with children of 3000-3999 g. Birth weight was also associated with increased risks of injury after adjusting for gestational age.

CONCLUSIONS

Children born with adverse neonatal conditions have a marked increased risk of injury. This suggests an opportunity to identify children who may benefit from injury prevention. More research is needed to identify the causal pathways driving these associations.