Maternal and paternal ages at conception of index child and risk of childhood acute leukaemia: A multicentre case-control study in Greater Mexico City

•In most of parental ages strata no association with leukaemia risk was found.•A positive association between risk of childhood ALL was observed with younger parental ages.•A positive association between risk of childhood AML was observed with younger parental ages. The parental age at conception has been reported to be a risk factor for childhood acute leukaemia (AL); however, the relationship is controversial. The aim of the present study was to investigate the association between parental age at conception and the risk of AL in Mexican children, a population with a high incidence of the disease and a high prevalence of pregnancies in adolescents and young adults. A multicentre case-control study was conducted. Incident AL cases younger than 17 years of age diagnosed between 2010 and 2015 were included. Controls were matched with cases according to age, sex, and health institution. Using logistic regression analysis, adjusted odds ratios (aOR) and 95 % confidence intervals (95 % CI) were calculated for each maternal stratum after adjusting for paternal age at conception of index child. The maternal age between 25 and 29.99 years was selected as the reference category. In most strata where maternal and paternal ages were assessed, no association was found with the risk of developing acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML) in their offspring. An increased risk for AML was observed when the mother was between 20 and 24.99 years of age and the father aged 25−29.99 years (aOR, 1.94; 95 % CI, 1.03–3.67). In addition, there was a positive association for ALL when the mother´s age was between 20 and 24.99 years and the father was