Authors:
Rudant J, Lightfoot T, Urayama KY, Petridou E, Dockerty JD, Magnani C, Milne E, et al.
Authors notes:
American journal of epidemiology. 2015;181(8):549-62.
Keywords:
breastfeeding, childhood leukemia, day care, infections
Abstract:
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.
Day-care center attendance in the first year of life was associated with a reduced risk of ALL, with a marked inverse trend with earlier age at start.
An inverse association was also observed with breastfeeding duration of 6 months or more.
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.