Maternal and birth anthropometric characteristics in relation to the risk of childhood lymphomas: a Swedish nationwide cohort study.

This Swedish nationwide cohort study aims to examine the role of maternal characteristics (maternal age, education, smoking, BMI, diabetes, and preeclampsia) and multiple intrauterine growth measures on the risk of childhood lymphomas. A total of 3 444 136 singleton live births registered in the Swedish Medical Birth Register were analyzed, among whom there were 515 incident non-Hodgkin lymphoma (NHL) cases and 169 Hodgkin lymphoma (HL) cases aged 0-14 years at diagnosis (1973-2007) identified through linkage with the Swedish Cancer Register. Proportional hazards models were used to estimate the hazard ratio (HR) and 95% confidence intervals (95% CI) of NHL and HL. Male sex (HR=2.00, 95% CI: 1.66-2.41), older maternal age (HR=1.03, 95% CI: 1.00-1.06, per 1-year increase), and large for gestational age compared with appropriate for gestational age (AGA) birth weight (HR=1.83, 95% CI: 1.20-2.79) were correlated with the risk of NHL; of note, in subanalysis by sex, the latter association was confined to girls (HR=3.37, 95% CI: 1.90-5.97, Pinteraction by sex=0.008). The risk of childhood HL overall was more evident among boys (HR=2.03, 95% CI: 1.46-2.81), whereas indices of accelerated fetal growth were not convincingly associated with the risk of HL. Apart from the established association with sex, the findings point to accelerated intrauterine growth as a risk factor for childhood NHL that may differ by sex. Given the rarity of this condition at birth, however, further studies with more elaborate indices are needed to conclude on its association with rare diseases such as HL.