a meta-analysis of prenatal and maternal risk factors for childhood leukemia in iran, case-control studies approach

Context: few possible risk factors for childhood leukemia including environmental, genetic, and infectious causes can be explained by epidemiologic studies but the etiology of most childhood leukemia is unknown. objectives: in this systematic review and meta-analysis, we aimed to find the relationship between prenatal and maternal risk factors with leukemia children in iran. data sources: relevant studies published in english databases (pubmed, scopus, and isi) and persian databases (magiran, medlib, sid, and iran medex)) were systematically searched. study selection: the study included all case-control studies that estimated the effects of prenatal and maternal risk factors on leukemia children in iran during years 2004 to 2016, and a standardized manner was used for the extraction of information. data extraction: after reviewing all searched articles (title, abstract, and entire text), irrelevant studies were excluded and related ones were selected. results:we identified 10 case-control studies. the first relative history of leukemia was associated with four times raises of leukemia in children aged 15 > years (or = 4.58, 95% ci = 1.16 - 7.99). other significant risk factors were mothers with birth order 3  and maternal age > 35, ors for these factors were respectively (or = 2.39, 95% ci = 0.79 - 3.99) and or = 2.25, 95% ci = 1.09 - 3.41). conclusions: our results indicate that among maternal and prenatal risk factors, birth order 3, birth weight < 2,500 g, and first relative history of leukemia increased the risk of childhood leukemia; in contrast, breastfeeding was a protective factor.