A recent study has shown, in children with brain tumors, higher birth weight appears to lead to higher body mass index (BMI) in childhood and may be useful in identifying patients at risk of future obesity. 
The study used cross-sectional data from 78 children with brain tumours (42.3 percent female) and 133 noncancer, healthy controls (45.1 percent female). BMI was calculated for all participants, and adiposity was determined using a body fat monitor and body composition analyzer.
Majority of the participants were born at full term (57.70 percent of patients; 48.90 percent of controls), but significantly more controls were born preterm (15.80 percent vs 3.80 percent; p=0.008). Early-term (p=0.32) and late-term (p=0.15) births were statistically comparable between the groups.
A multivariable logistic regression analysis, adjusted for age, puberty, sex and percentage fat mass, showed that birth weight was significantly correlated with childhood BMI. Specifically, for every unit increase in birth weight, BMI increased by 0.18 units (95 pe0rcent CI, 0.03–0.33; p=0.02) in patients and by 0.17 units (0.07–0.27; p=0.001) in controls.
BMI z-scores also significantly increased by 3.69 (1.12–6.25; p=0.006) and 2.15 (0.75–3.55; p=0.003) units in patients and controls, respectively, for every unit increase in birth weight.
The effect of birth weight on childhood BMI (p=0.08) and BMI z-scores (p=0.13) was statistically comparable between controls and patients.
The researchers said, “The emergence of cardiovascular diseases and type 2 diabetes in survivors of childhood brain tumours are likely to contribute to adverse prognoses, and there is an urgent need to identify the drivers of these outcomes to mitigate their effects on the lifespan and quality of life,”. 
They added, “In this study, we demonstrate that birth weight is a risk factor for higher body mass in [children with brain tumours] during childhood, and this relationship was similar to that noted in nonancer controls,”