Birth weight 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: 1.08–1.58) 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.