Lung function after extremely preterm birth-A population-based cohort study (EXPRESS)

Research output: Contribution to journalArticle


BACKGROUND AND OBJECTIVES: Follow-up studies of children and young adults born very-to-moderately preterm show persistent and significant lung function deficits. The aim of the study was to determine lung function and airway mechanics in school-aged children born in 2004 to 2007 and extremely preterm (after 22-26 weeks of gestation).

METHODS: In a population-based cohort of children born extremely preterm and controls born at term (n = 350), follow-up at 6½-years-of-age was performed using spirometry and impulse oscillometry. Associations to gestational age, smallness for gestational age (SGA), and bronchopulmonary dysplasia (BPD) were assessed.

RESULTS: Children born extremely preterm had lower forced vital capacity (FVC, z-score: -0.7, 95%CI: -1.0;-0.4), forced expiratory volume (FEV1 , z-score: -1.1, 95%CI: -1.4; -0.8), higher frequency-dependence of resistance (R5-20 , 0.09, 95%CI: 0.05; 0.12 kPa · L-1  · s-1 ) and larger area under the reactance curve (AX, 0.78, 95%CI: 0.49; 1.07 kPa · L-1 ) than controls. In children born at 22-24 weeks of gestation, 24% had FVC and 44% had FEV1 below the lower limit of normal. SGA and severe BPD only marginally contributed to pulmonary outcomes. Asthma-like disease was reported in 40% of extremely preterm children and 15% of controls.

CONCLUSION: Many children born extremely preterm have altered airway mechanics and significant obstructive reduction in lung function. This warrants consideration for treatment and continued follow-up.


External organisations
  • Umeå University
  • Karolinska Institutet
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Respiratory Medicine and Allergy
  • Pediatrics


  • Asthma/physiopathology, Bronchopulmonary Dysplasia/physiopathology, Child, Cohort Studies, Female, Follow-Up Studies, Forced Expiratory Volume, Humans, Infant, Extremely Premature/physiology, Infant, Newborn, Lung/physiopathology, Male, Premature Birth/physiopathology, Respiratory Function Tests, Spirometry, Vital Capacity
Original languageEnglish
Pages (from-to)64-72
JournalPediatric Pulmonology
Issue number1
Publication statusPublished - 2018 Jan
Publication categoryResearch

Bibliographic note

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