Birth weight, sex and childhood cancer: A report from the United Kingdom Childhood Cancer Study

Abstract Birth weight has been linked to the risk of developing childhood cancer, in particular childhood leukaemia. However, despite many childhood cancers having a male predominance and boys generally weighing more than girls at birth few studies have reported sex-specific associations. The relationship between birth weight and childhood cancer risk was examined using information from a national case-control study. Children (0–14 years) newly diagnosed with cancer in GB were ascertained between 1991 and 1996 ( n = 3651) and for comparison, controls matched on sex, month and year of birth were identified from primary care population registers ( n = 6337). Birth weights were obtained from the Office of National Statistics for all targeted subjects born in England and Wales. Overall, cases were, on average, 30 g heavier at birth than controls ( p = 0.003) with differences seen by cancer type; those diagnosed with hepatic tumours weighing around 500 g less than controls at birth ( p < 0.0001) and those with leukaemia being, on average, 50 g heavier than those without ( p = 0.001). An interaction between birth weight and sex was found for acute leukaemia ( χ2 = 11.2, p = 0.04) and when data were stratified by sex, an association between high birth weight and risk of ALL was seen with girls (>4000 g, OR 1.86, 95% CI 1.38–2.50, χ2 for trend 20.2, p < 0.0001). Our results support the hypothesis that birth weight is an important determinant for childhood cancer. In addition, the data are consistent with the notion that childhood leukaemia has a prenatal origin.