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The impact of birth mode of delivery on childhood asthma and allergic diseases–a sibling study

BACKGROUND: Caesarean section (CS) has been reported to increase the risk of asthma in offspring. This may be due to that infants delivered by CS are unexposed to vaginal flora, according to the ‘hygiene hypothesis’. OBJECTIVE: Our aim was to investigate if CS increases risk of childhood asthma, and...

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Autores principales: Almqvist, C, Cnattingius, S, Lichtenstein, P, Lundholm, C
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Blackwell Publishing Ltd 2012
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3564396/
https://www.ncbi.nlm.nih.gov/pubmed/22925323
http://dx.doi.org/10.1111/j.1365-2222.2012.04021.x
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author Almqvist, C
Cnattingius, S
Lichtenstein, P
Lundholm, C
author_facet Almqvist, C
Cnattingius, S
Lichtenstein, P
Lundholm, C
author_sort Almqvist, C
collection PubMed
description BACKGROUND: Caesarean section (CS) has been reported to increase the risk of asthma in offspring. This may be due to that infants delivered by CS are unexposed to vaginal flora, according to the ‘hygiene hypothesis’. OBJECTIVE: Our aim was to investigate if CS increases risk of childhood asthma, and if the risk increase remains after adjustment for familial confounding using sibling design. METHODS: A register-based cohort study with 87 500 Swedish sibling pairs was undertaken. Asthma outcome variables were collected from national health registers as diagnosis or asthma medication (ICD-10 J45-J46; ATC code R03) during the 10th or 13th year of life (year of follow-up). Mode of delivery and confounders were retrieved from the Medical Birth Register. The data were analysed both as a cohort and with sibling control analysis which adjusts for unmeasured familial confounding. RESULTS: In the cohort analyses, there was an increased risk of asthma medication and asthma diagnosis during year of follow-up in children born with CS (adjusted ORs, 95% CI 1.13, 1.04–1.24 and 1.10, 1.03–1.18 respectively). When separating between emergency and elective CS the effect on asthma medication remained for emergency CS, but not for elective CS, while both groups had significant effects on asthma diagnosis compared with vaginal delivery. In sibling control analyses, the effect of elective CS on asthma disappeared, while similar but non-significant ORs of medication were obtained for emergency CS. CONCLUSIONS AND CLINICAL RELEVANCE: An increased risk of asthma medication in the group born by emergency CS, but not elective, suggests that there is no causal effect due to vaginal microflora. A more probable explanation should be sought in the indications for emergency CS.
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spelling pubmed-35643962013-02-08 The impact of birth mode of delivery on childhood asthma and allergic diseases–a sibling study Almqvist, C Cnattingius, S Lichtenstein, P Lundholm, C Clin Exp Allergy Original Articles BACKGROUND: Caesarean section (CS) has been reported to increase the risk of asthma in offspring. This may be due to that infants delivered by CS are unexposed to vaginal flora, according to the ‘hygiene hypothesis’. OBJECTIVE: Our aim was to investigate if CS increases risk of childhood asthma, and if the risk increase remains after adjustment for familial confounding using sibling design. METHODS: A register-based cohort study with 87 500 Swedish sibling pairs was undertaken. Asthma outcome variables were collected from national health registers as diagnosis or asthma medication (ICD-10 J45-J46; ATC code R03) during the 10th or 13th year of life (year of follow-up). Mode of delivery and confounders were retrieved from the Medical Birth Register. The data were analysed both as a cohort and with sibling control analysis which adjusts for unmeasured familial confounding. RESULTS: In the cohort analyses, there was an increased risk of asthma medication and asthma diagnosis during year of follow-up in children born with CS (adjusted ORs, 95% CI 1.13, 1.04–1.24 and 1.10, 1.03–1.18 respectively). When separating between emergency and elective CS the effect on asthma medication remained for emergency CS, but not for elective CS, while both groups had significant effects on asthma diagnosis compared with vaginal delivery. In sibling control analyses, the effect of elective CS on asthma disappeared, while similar but non-significant ORs of medication were obtained for emergency CS. CONCLUSIONS AND CLINICAL RELEVANCE: An increased risk of asthma medication in the group born by emergency CS, but not elective, suggests that there is no causal effect due to vaginal microflora. A more probable explanation should be sought in the indications for emergency CS. Blackwell Publishing Ltd 2012-09 2012-08-28 /pmc/articles/PMC3564396/ /pubmed/22925323 http://dx.doi.org/10.1111/j.1365-2222.2012.04021.x Text en Copyright © 2012 Blackwell Publishing Ltd http://creativecommons.org/licenses/by/2.5/ Re-use of this article is permitted in accordance with the Creative Commons Deed, Attribution 2.5, which does not permit commercial exploitation.
spellingShingle Original Articles
Almqvist, C
Cnattingius, S
Lichtenstein, P
Lundholm, C
The impact of birth mode of delivery on childhood asthma and allergic diseases–a sibling study
title The impact of birth mode of delivery on childhood asthma and allergic diseases–a sibling study
title_full The impact of birth mode of delivery on childhood asthma and allergic diseases–a sibling study
title_fullStr The impact of birth mode of delivery on childhood asthma and allergic diseases–a sibling study
title_full_unstemmed The impact of birth mode of delivery on childhood asthma and allergic diseases–a sibling study
title_short The impact of birth mode of delivery on childhood asthma and allergic diseases–a sibling study
title_sort impact of birth mode of delivery on childhood asthma and allergic diseases–a sibling study
topic Original Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3564396/
https://www.ncbi.nlm.nih.gov/pubmed/22925323
http://dx.doi.org/10.1111/j.1365-2222.2012.04021.x
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