Birth order and childhood type 1 diabetes risk: a pooled analysis of 31 observational studies.

Background: The incidence rates of childhood onset type 1 diabetes are almost universally increasing across the globe but the aetiology of the disease remains largely unknown. We investigated whether birth order is associated with the risk of childhood diabetes by performing a pooled analysis of previous studies.

Methods: Relevant studies published before January 2010 were identified from MEDLINE, Web of Science and EMBASE.