Birthweight and subsequent risk of childhood primary brain tumors: An updated meta-analysis

Background: Primary brain tumors are common in childhood, but the etiology is largely unclear. As studies on birth weight as a risk factor for the occurrence of histologically specified tumors have been inconclusive, we decided to update a 2008 meta-analysis on the subject. Methods: A search strategy was performed in Medline and EMBASE for the period 2007-2016. We included six new studies and performed further subgroup analyses for medulloblastoma and primitive neuroectodermal tumors (PNETs). Dichotomous analyses were performed for low (2,500 g) and high birth weight (4,000 g cutoff point). Results: Our results confirmed that high birth weight increases the risk of astrocytoma (odds ratio [OR] = 1.60, 95% confidence interval [CI]: 1.23-2.09) and medulloblastoma/PNET. However, subgroup analysis revealed an increased risk of medulloblastoma (OR = 1.31, 95% CI: 1.081.58) but not of PNET (OR = 1.16, 95% CI: 0.92-1.46). Low birth weight was associated with an increased risk of medulloblastoma/PNET. Subgroup analysis for medulloblastoma and PNET revealed increased risk but CIs included zero. Neither low nor high birth weight was associated with the risk of ependymoma. Conclusions: While an association between high birth weight and astrocytoma was confirmed, more studies are needed to investigate medulloblastoma and PNET risk in children with high and low birth weight.