biostudies-literatureRudant JNIEHS NIH HHSNCI NIH HHS549-62https://www.ebi.ac.uk/biostudies/studies/S-EPMC4850899biostudies-literatureUnknown181(8)The associations between childhood acute lymphoblastic leukemia (ALL) and several proxies of early stimulation of the immune system, that is, day-care center attendance, birth order, maternally reported common infections in infancy, and breastfeeding, were investigated by using data from 11 case-control studies participating in the Childhood Leukemia International Consortium (enrollment period: 1980-2010). The sample included 7,399 ALL cases and 11,181 controls aged 2-14 years. The data were collected by questionnaires administered to the parents. Pooled odds ratios and 95% confidence intervals were estimated by unconditional logistic regression adjusted for age, sex, study, maternal education, and maternal age. Day-care center attendance in the first year of life was associated with a reduced risk of ALL (odds ratio = 0.77, 95% confidence interval: 0.71, 0.84), with a marked inverse trend with earlier age at start (P < 0.0001). An inverse association was also observed with breastfeeding duration of 6 months or more (odds ratio = 0.86, 95% confidence interval: 0.79, 0.94). No significant relationship with a history of common infections in infancy was observed even though the odds ratio was less than 1 for more than 3 infections. The findings of this large pooled analysis reinforce the hypothesis that day-care center attendance in infancy and prolonged breastfeeding are associated with a decreased risk of ALL.American journal of epidemiologyChildhood acute lymphoblastic leukemia and indicators of early immune stimulation: a Childhood Leukemia International Consortium study.PMC4850899R03CA132172R13 ES021145-01R01 ES09137R01CA0494501R13 ES024632-01P42-ES04705R01CA0480511R13 CA174342-01P01 ES018172Lightfoot TMiller MRondelli RClavel JMagnani COrsi LDockerty JDAshton LJDessypris NRoman EInfante-Rivard CRudant JSimpson JMetayer CStiakaki EUrayama KYPetridou ESpector LGMilne EKang AYfalseChildhood acute lymphoblastic leukemia and indicators of early immune stimulation: a Childhood Leukemia International Consortium study.The associations between childhood acute lymphoblastic leukemia (ALL) and several proxies of early stimulation of the immune system, that is, day-care center attendance, birth order, maternally reported common infections in infancy, and breastfeeding, were investigated by using data from 11 case-control studies participating in the Childhood Leukemia International Consortium (enrollment period: 1980-2010). The sample included 7,399 ALL cases and 11,181 controls aged 2-14 years. The data were collected by questionnaires administered to the parents. Pooled odds ratios and 95% confidence intervals were estimated by unconditional logistic regression adjusted for age, sex, study, maternal education, and maternal age. Day-care center attendance in the first year of life was associated with a reduced risk of ALL (odds ratio = 0.77, 95% confidence interval: 0.71, 0.84), with a marked inverse trend with earlier age at start (P < 0.0001). An inverse association was also observed with breastfeeding duration of 6 months or more (odds ratio = 0.86, 95% confidence interval: 0.79, 0.94). No significant relationship with a history of common infections in infancy was observed even though the odds ratio was less than 1 for more than 3 infections. The findings of this large pooled analysis reinforce the hypothesis that day-care center attendance in infancy and prolonged breastfeeding are associated with a decreased risk of ALL.2015-01-01T00:00:00Z2015 Apr2026-05-29T18:19:28.548Z2019-03-27T02:12:44ZS-EPMC48508992573188810.1093/aje/kwu298