title: Cesarean Section and Risk of Childhood Acute Lymphoblastic Leukemia in a Population-Based, Record-Linkage Study in California.
abstract: The relationship of mode of delivery to risk of childhood acute lymphoblastic leukemia (ALL) is uncertain. After linking birth records and cancer registry data from California, we conducted a population-based case-control study to investigate the role of delivery by cesarean section (C-section) in the etiology of childhood ALL. This study included 5,081 cases and 18,927 matched controls born in 1978-2009; more detailed data were available on type of C-section (i.e., elective vs. emergency) for a subset of 1,552 cases and 5,688 controls. No association was observed between C-section overall and childhood ALL risk (<15 years of age), but elective C-section was associated with a significantly elevated risk of ALL (odds ratio (OR) = 1.17, 95% confidence interval (CI): 1.01, 1.36). At the peak ages of ALL incidence (2-4 years), C-section was associated with an 11% higher risk of ALL (OR = 1.11, 95% CI: 1.01, 1.22) compared with vaginal delivery, and the magnitude of the association was larger for elective C-section (OR = 1.38, 95% CI: 1.11, 1.70). Emergency C-section was not associated with childhood ALL. Because of design features minimizing nonparticipation and inaccurate recall, this record linkage-based study is less prone to bias. Our results suggest that delivery by elective C-section was associated with a higher risk of childhood ALL, especially at the peak ages of incidence. It is important to evaluate possible mechanisms, because this potential risk factor is modifiable.
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Wiemels
authors.forename: Catherine
authors.initials: C
authors.lastname: Metayer
authors.forename: Libby
authors.initials: L
authors.lastname: Morimoto
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Francis
authors.forename: Nina
authors.initials: N
authors.lastname: Kadan-Lottick
authors.forename: Andrew T
authors.initials: AT
authors.lastname: DeWan
authors.forename: Yawei
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Ma
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D016022:Case-Control Studies; D002585:Cesarean Section / Q000009:adverse effects*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D016017:Odds Ratio; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000453:epidemiology / Q000209:etiology*; D055815:Young Adult
keywords: acute lymphoblastic leukemia; case-control studies; cesarean section; child; leukemia; microbiome