Pre- and perinatal risk factors for childhood leukaemia and other malignancies: a Scottish case control study

A case control study of Scottish children aimed to identify risk factors fo r leukaemia and other cancers operating in the prenatal environment, during delivery and neonatally. Cases (0-14 years) were age-and sex- matched to t wo population-based controls and details abstracted from the mother's hospi tal obstetric notes. Analyses of 144 leukaemias (124 acute lymphoblastic le ukaemias (ALL)), 45 lymphomas, 75 central nervous system (CNS) tumour and 1 26 'other solid tumours' were conducted using conditional logistic regressi on. The presence of a neonatal infection significantly reduced the risk of ALL (odds ratio (OR) 0.49, 95% confidence interval (CI) 0.26-0.95), particu larly in 0- to 4-year-olds. Positive swab tests confirmed 47% of ALL cases with any infection and 46% of controls. This is consistent with the hypothe sis that early exposure to infections may reduce the risk of childhood ALL. Asphyxia at birth significantly increased the risk of leukaemia, which was accounted far by ALL. For the 'other solid tumours' higher levels of mater nal education were inversely associated with risk (OR 0.59, 95% GI 0.37-0.9 4) but positively associated with antibiotics (OR 2.16 95% GI 1.10-4.25) an d respiratory tract infections (OR 14.1, 95% CI 1.76-113.7) in pregnancy. N o obvious plausible patterns of risk were detected either within or across disease subgroups.