Preterm birth intrinsically changes the normal development of lung function, according to a study published in the first issue for January of the American Thoracic Society’s peer-reviewed American Journal of Respiratory and Critical Care Medicine.
Lead author Ola Hjalmarson, M.D., Ph.D., of the Department of Pediatrics, Göteborg University, Göteburg, Sweden, along with an associate, said that premature birth per se has "evident implications for lung volume, mechanics of breathing, gas mixing efficiency, and ventilation. . ." compared with those who are born at term.
In the study, the authors designed their research to assess the consequences of preterm birth on the functional development of the lungs.
They studied 32 healthy preterm infants whose gestational age ranged from 25 to 33 weeks at birth, and compared them with 53 healthy full-term infants (37 to 42 weeks).
"In preterm infants, lung development normally taking place in utero will instead occur after birth and under very different conditions," said Dr. Hjalmarson. "Those conditions include active breathing with strain and relaxation of immature lung tissue, as well as lung perfusion with full cardiac output and with exposure to considerably higher oxygen tension than during fetal life."
The study was designed to compare healthy preterm infants without any history of lung disease, with healthy term infants at the same postmenstrual age, close to term. The aim of this study was to assess the consequences of preterm birth for functional development of the lungs over the period from premature birth until term.
The authors said that the lung function abnormalities in healthy preterm infants shown in their study reflect disturbances in lung development that may have started before or after birth.
Several postnatal conditions may adversely affect lung development in preterm infants during a period corresponding to the last trimester of pregnancy.
They include: mechanical forces related to breathing; exposure of epithelial cells (cell layers that form the lining of hollow organs) and endothelial cells (layer of flat cells that line some body cavities) to higher oxygen tension than during fetal life; influence of air flow on airway epithelium; absence of the distending effect of lung fluid; changes of lung perfusion and lung volume, and absence of maternal and placental factors, including the nutritional and endocrine differences between the fetal and extrauterine environment.
[Contact: Ola Hjalmarson M.D. Ph.D.]