1. Greater airway obstruction in adolescence was observed in both females and males who were born moderate-to-late preterm compared to term controls.
2. No evidence of catch-up in lung function was observed between 8 and 16 years of age.
Evidence Rating Level: 2 (Good)
Study Rundown: Lung development in preterm infants (<37 weeks’ gestation) is often incomplete, which can lead to perinatal complications including apnea and respiratory distress syndrome. Some evidence suggests that lung immaturity at birth may also have long-term consequences, extending at least into early childhood for moderate-to-late preterm babies (32-36 weeks’ gestation) and beyond for very preterm infants (<32 weeks’ gestation). To investigate whether such findings for moderate-to-late preterm babies persisted into adolescence, this study performed pulmonary function testing at the ages of 8 and 16 years in a cohort of moderate-to-late preterm infants and term controls. Spirometry results suggested that both male and female babies born between 32 and 36 weeks’ gestation had reduced airway function at the ages of 8 and 16. Increased frequency dependence of resistance at 16 years of age was also observed in the male participants. Although other studies have suggested the possibility of some improvement in preemie lung function over time, the results of the present study are consistent with a persistent decrease in airway function through adolescence compared to term controls. As a bronchodilator test was not performed, it is unclear whether the suggested increase in airway resistance is attributable to reversible obstruction (e.g., asthma) or the result of incomplete lung development. Regardless, these findings suggest that continuing to monitor lung function and symptomatically treating preemies that show signs of decreased respiratory function at birth and in childhood may be beneficial.
In-Depth [prospective cohort]: Participants included 149 moderate-to-late preterm (32-36 weeks’ gestation) and 2472 term (37-41 weeks’ gestation) infants of the BAMSE (Swedish abbreviation for Children, Allergy, Milieu, Stockholm, Epidemiology) study for which lung function data was available. Respiratory symptoms (e.g., asthma and wheeze) were obtained by questionnaire, and pulmonary function testing was performed at 8 and 16 years. Additional testing to assess frequency dependence of resistance (by impulse oscillometry [IOS]) was conducted at 16 years. Adjusting for height, age, and maternal smoking during pregnancy, significant differences in forced expiratory volume in 1 second (FEV1) and FEV1 normalized for forced vital capacity (FEV1/FVC) were observed in both moderate-to-late premature males and females at age 16 compared to term adolescents (difference in FEV1 for females = -116 mL, p = 0.02; for males = -177 mL, p = 0.02; difference in FEV1/FVC for females = -2.9%, p < 0.001; for males = -2.5%, p = 0.01). Such trends of decreased FEV1 and FEV1/FVC were also observed at age 8 for both genders, but only the difference in FEV1 in females (p = 0.02) and FEV1/FVC in males (p = 0.03) were significant. The IOS testing at 16 years of age demonstrated a significant increase in the median of frequency dependence of resistance (R5-20) for males born between 32 and 36 weeks compared to term controls (20.9 PaL-1s-1, p < 0.001). The difference in median values for females also trended in this direction, but did not reach significance.
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