loading page

Influenza Hospitalizations during Childhood in Children born Preterm
  • +1
  • Siri Hauge,
  • Birgitte De Blasio,
  • Siri E Håberg,
  • Laura Oakley
Siri Hauge
Norwegian Institute of Public Health
Author Profile
Birgitte De Blasio
Norwegian Institute of Public Health
Author Profile
Siri E Håberg
Norwegian Institute of Public Health
Author Profile
Laura Oakley
London School of Hygiene & Tropical Medicine
Author Profile


Objective: To determine if children born preterm were at increased risk of influenza hospitalization up to age five. Methods: National registry data on all children born in Norway between 2008 and 2011 was used in Cox regression models to estimate adjusted hazard ratios (aHR) for influenza hospitalizations up to age five in children born preterm (<37 pregnancy weeks). HRs were also estimated separately for very preterm (<32 weeks), early term (37-38 weeks), and post-term (≥42 weeks) children. Results: Among 238 628 children born in Norway from January 2008 to December 2011, 15 086 (6.3%) were born preterm. There were 754 (0.3%) children hospitalized with influenza before age five. The rate of hospitalizations in children born preterm was 1.4 per 10 000 person-years (95% confidence interval [CI]: 1.1-1.7), and 0.6 per 10 000 person-years (95% CI: 0.5-0.6) in children born at term (≥37 weeks). Children born preterm had a higher risk of influenza hospitalization before age 5: aHR 2.33 (95% CI: 1.85-2.93). The risk increased with decreasing gestational age and was highest among those born very preterm; aHR 4.07 (95% CI: 2.63-6.31). Compared to children born at 40-41 weeks, children born early term also had an elevated risk of influenza hospitalization; aHR (37 weeks) 1.89 (95% CI: 1.43-2.40), aHR (38 weeks) 1.43 (95% CI: 1.15-1.78). Conclusion: Children born preterm had a higher risk of influenza hospitalizations before age five. An elevated risk was also present among children born at an early term. Children born preterm would benefit from influenza vaccinations.

Peer review status:UNDER REVIEW

01 Apr 2021Submitted to Influenza and other respiratory viruses
03 Apr 2021Assigned to Editor
03 Apr 2021Submission Checks Completed
16 Apr 2021Reviewer(s) Assigned