Summary of the results for childhood ALL in relation to maternal smoking during pregnancy: subgroup analyses.

Abbreviations: OR, odds ratio.aHiggins’ I2 statistic and 95%CI, are shown for a measure of the degree of heterogeneity across studies.bcEurope counties include Italy, France, Sweden, United Kingdom, Greece. Others include America, Canada, Australia, Israel, Brazil.d“high” means the score of quality range from 7 to 9, “moderate” means the score is among 4 to 6.Summary of the results for childhood ALL in relation to maternal smoking during pregnancy: subgroup analyses.