Pre-pregnancy obesity and childhood malignancies: A population-based cohort study

Objective: Exploring the effect of maternal obesity during pregnancy on the long-term health of offspring is of great importance. The aim of this study was to evaluate the association between maternal pre-pregnancy obesity and future risk of childhood malignancies. Study design: A population-based cohort analysis comparing the risk for long-term childhood malignancies (up to the age of 18 years) in children born (1991-2014) to mothers with and without pre-pregnancy obesity (body mass index > 30) was conducted in July 2017. Childhood malignancies were predefined based on ICD-9 codes, as recorded in the hospital medical files. Children with congenital malformations and multiple gestations were excluded from the analysis. The Kaplan-Meier survival curve was constructed to compare cumulative oncological morbidity in both groups over time. The Cox proportional hazards model was used to control for confounders. Results: During the study period, 241 273 infants met the inclusion criteria; 3268 were born to mothers with pre-pregnancy obesity. Children of obese women had significantly increased risk for several childhood malignancies (including brain tumors) as well as increased risk for total hospitalizations with malignancy diagnoses, even after controlling for several confounders (adjusted HR 1.90, 95% CI 1.07-3.37, P = 0.028). Cumulative incidence of oncological morbidity was also significantly increased over time in the studied group (log-rank P = 0.023). Conclusion: Maternal pre-pregnancy obesity is significantly associated with an increased long-term risk for general childhood malignancies, and specifically brain tumors in the offspring. These results are important when counseling mothers regarding potential future risks and recommended lifestyle modifications.