1 Pediatrician, Department of Pediatrics, Faculty of Medicine, Mashhad university of Medical Sciences, Mashhad, Iran.

2 Department of Surgery, Faculty of Medicine, Kashan University of Medical Sciences, Kashan, Iran.

3 Fellowship of Pediatric Intensive Care, Department of Pediatrics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.

4 General Physician, Mashhad University of Medical Sciences Mashhad, Iran.

5 MSc Counseling in Midwifery, Department of Nursing and Midwifery, Neyshabur University of Medical Sciences, Neyshabur, Iran.

6 Nursing Research Center, Department of Critical Care Nursing, Kerman University of Medical Sciences, Kerman, Iran.

7 Department of Reproductive Health and Midwifery, School of Nursing and Midwifery, Iran University of Medical Sciences, Tehran, Iran.

8 Student Research Committee, Kerman University of Medical Sciences, Kerman, Iran.


Background: Numerous meta-analyses of childhood leukemia have been published, but no comprehensive study has examined the factors influencing childhood leukemia. We aimed to scrutinize the modifiable and non-modifiable factors affecting the risk of childhood leukemia.
Materials and Methods: In this overview, two independent researchers screened the articles studying the effect of modifiable and non-modifiable factors on the childhood leukemia from the related databases, including Scopus, EMBASE, Cochrane, Web of Science, and Medline, without time and language restrictions from inception up to March 10, 2020.
Results: Eight meta-analyses were included in this overview. Breastfeeding compared with non-breastfeeding was associated with 9% reduction in the risk of childhood leukemia (OR = 0.91). The children with the birth weight of ≥4,000 g were at a higher risk of acute lymphoblastic leukemia compared with those with low birth weight (OR = 1.26, 95% CI = 1.17, 1.37). There was a significant relationship between childhood leukemia and residential pesticide exposure (SOR=1.57). There was a relationship between influenza during pregnancy and higher risk of ALL (POR=3.64; 95% CI = 1.34-9.90), and childhood leukemia (POR=1.77). The childhood AML had a statistically significant relationship with no alcohol consumption during pregnancy. The SOR of childhood ALL had an association with paternal smoking. A statistical relationship exists between magnetic field intensity of ≥0.4 μT and childhood leukemia. The exposure to NO2 and benzene exhibited the OR of 1.64 (95% CI = 0.91-2.95) and 1.21 (95% CI = 0.97-1.52), respectively.
Conclusion: Decreased breastfeeding, high birth weight, viral infections during pregnancy, alcohol consumption, maternal exposure to direct and indirect smoking, and exposure to electromagnetic fields and airborne pollutants are found to be significant risk factors for childhood leukemia.