Caesarean Section and Risk of Respiratory Tract Infections During Infancy

Sarfaroj Khan 


February 23, 2021


  • The risk of severe lower respiratory tract infection (LRTI) admission during infancy is 10-39% higher in infants born by planned caesarean.

  • Planned or emergency caesarean section is an independent risk factor associated with a 9-11% increase in the risk of upper respiratory tract infection (URTI) admission.

Why this matters

  • Caesarean section has been linked with LRTI in the child in several studies, and URTI is common during childhood; limited studies have examined if caesarean section is also a risk factor for this site of infection.

Study design

  • This study included 15,580 term-born singleton infants from the Millennium Cohort Study (MCS; 2000-2002) and 392,145 infants from the Secure Anonymized Information Linkage (SAIL; 2002-2016) database.

  • Funding: National Institute for Health Research Policy Research Programme.

Key results

  • LRTI:

    • hospital admission rate was 4.6 and 5.9 per 100 child-years in the MCS and SAIL cohorts, respectively.

    • emergency caesarean was not associated with LRTI admission in both cohorts.

    • planned caesarean was associated with an increased risk of LRTI admission (adjusted HR [aHR], 1.39; 95% CI, 1.03-1.87 in the MCS and aHR, 1.10; 95% CI, 1.05-1.15 in SAIL).

    • when gestation age was not accounted for, the aHR increased to 1.65 (95% CI, 1.24-2.19) in the MCS and to 1.17 (95% CI, 1.12-1.22) in SAIL.

  • URTI (information was available solely in the SAIL cohort):

    • hospital admission rate was 5.9 per 100 child-years.

    • emergency caesarean was associated with an increased risk of URTI admission (aHR, 1.09; 95% CI, 1.05-1.14).

    • planned caesarean was associated with an aHR of 1.11; 95% CI, 1.06-1.16, which increased to 1.17 (95% CI, 1.12-1.22) when the gestational age was not adjusted for.


  • Unavailability of information about URTI admissions in the MCS.

  • Risk of bias.


Alterman N, Kurinczuk JJ, Quigley MA. Caesarean section and severe upper and lower respiratory tract infections during infancy: Evidence from two UK cohorts. PLoS One. 2021;16(2):e0246832. doi: 10.1371/journal.pone.0246832. PMID: 33592033 View abstract 

This clinical summary originally appeared on Univadis, part of the Medscape Professional Network.


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