Birth order and risk of childhood cancer in the Danish birth cohort of 1973–2010
- 289 Downloads
Many studies have investigated the possible association between birth order and risk of childhood cancer, although the evidence to date has been inconsistent. Birth order has been used as a marker for various in utero or childhood exposures and is relatively straightforward to assess.
Data were obtained on all children born in Denmark between 1973 and 2010, involving almost 2.5 million births and about 5,700 newly diagnosed childhood cancers before the age of 20 years. Data were analyzed using Poisson regression models.
We failed to observe associations between birth order and risk of any childhood cancer subtype, including acute lymphoblastic leukemia; all rate ratios were close to one. Further analyses stratified by birth cohort (those born between 1973 and 1990, and those born between 1991 and 2010) also failed to show any associations. Considering stillbirths and/or controlling for birth weight and parental age in the analyses had no effect on the results. Analyses by years of birth (those born between 1973 and 1990, and those born between 1991 and 2010) did not show any changes in the overall pattern of no association.
In this large cohort of all children born in Denmark over an almost 40-year period, we did not observe an association between birth order and the risk of childhood cancer.
KeywordsBirth order Childhood cancer Leukemia Risk factors Denmark
Acute lymphoblastic leukemia
Acute myeloblastic leukemia
Central nervous system
95 % Confidence interval
No specific funding was obtained for this study. Costs for data retrieval were covered by the collaboration agreement between the IARC and the Danish Cancer Society Research Center.
Compliance with ethical standards
Conflict of interest
None of the authors declared any conflict of interest.
Human and animal rights
The study did not involve personal contact with human subjects and no animals. The study is based on record linkage of various registers in Denmark and was therefore approved by “Datatilsynet” (the Danish Data Protection Board). No informed consent from individuals was required.
- 1.Little J (1999) Epidemiology of childhood cancer. IARC Science Publication, Lyon, p 149Google Scholar
- 7.Marcotte EL, Ritz B, Cockburn M, Yu F, Heck JE (2014) Exposure to infections and risk of leukemia in young children. Cancer Epidemiol Biomarker Prev 23(7):1195–1203Google Scholar
- 8.Rudant J, Lightfoot T, Urayama KY, Petridou E, Dockerty JD, Magnani C, Milne L, Spector LG, Ashton L, Dessypris N, Kang AY, Miller M, Rondelli R, Simpson J, Stiakaki E, Orsi L, Roman E, Metayer C, Infante-Rivard C, Clavel J (2015) Childhood acute lymphoblastic leukemia and indicators of early immune stimulation: a childhood leukemia international consortium (CLIC). Am J Epidemiol 181:549–562CrossRefPubMedGoogle Scholar
- 10.Schmidt LS, Kamper-Jørgensen M, Schmiegelow K, Johansen C, Lähteenmäki P, Träger C, Stokland T, Grell K, Gustafson G, Kogner P, Sehested A, Schüz J (2010) Infectious exposure in the first years of life and risk of central nervous system tumours in children: analysis of birth order, childcare attendance and seasonality of birth. Br J Cancer 102(11):1670–1675PubMedCentralCrossRefPubMedGoogle Scholar
- 20.Roman E, Simpson J, Ansell P, Kinsey S, Mitchell CD, McKinney PA, Birch JM, Greaves M (2007) Eden T; United Kingdom Childhood Cancer Study Investigators. Childhood acute lymphoblastic leukemia and infections in the first year of life: a report from the United Kingdom Childhood Cancer Study. Am J Epidemiol 165(5):496–504CrossRefPubMedGoogle Scholar
- 36.SAS/STAT software, Version 9.3 of the SAS System for Windows. Copyright © 2002–2010 SAS Institute Inc. SAS and all other SAS Institute Inc. product or service names are registered trademarks or trademarks of SAS Institute Inc., Cary, NC, USAGoogle Scholar
- 40.Petersen AN (editor). Børns levevilkår [Childrens living conditions]. Statistics Denmark 2002; Statistics Denmark Printing, Copenhagen; ISBN 87-501-1286-4Google Scholar