The effect of moderate-to-late preterm birth on lung function over the first 5 years of life in a South African birth cohort.

BACKGROUND

Preterm birth is associated with increased mortality and morbidity, particularly due to lung disease. Low- and middle-income countries (LMIC) have the highest rates of preterm birth. Infants born extremely preterm rarely survive, so the largest burden is amongst moderate-to-late preterm (MLP) infants. The long-term health impact on MLP children in LMIC is poorly understood. The aim of this study was to assess the effect of MLP birth on lung function trajectories from birth to 5 years in the Drakenstein Child Health Study.

METHODS

Children were followed from birth with lung function measurements at 6 weeks and annually until 5 years. Exposures were longitudinally collected from the antenatal period through to 5 years of age. Lung function tests included spectral and intra-breath oscillometry, tidal breathing and multiple breath washout. Mixed-effect models adjusted using a minimum set of variables were used.

RESULTS

Of 923 children, 119 (13%) were born MLP (32- <37 weeks' gestation; median gestational age 35 weeks) and 19 (2%) at <32 weeks' gestation. Children born MLP had altered lung function trajectories. Spectral oscillometry demonstrated a 13% reduction in compliance (0.87, 95% CI: 0.82-0.92), 5% increase in resistance at end expiration (1.05, 95% CI: 1.01-1.09) and 1.74 Hz (95% CI: 1.10-2.39) increase in resonance frequency over 5 years compared to term children. The proportion of children hospitalised for lower respiratory tract infections (LRTI) was higher in preterm-born children (29 (23.6%) MLP; 18 (94.7%) extreme to very preterm; 109 (14%) term-born children; p<0.01). LRTI and tobacco smoke exposure were associated with impaired lung function, but the impact of MLP on lung function was independent of these.

CONCLUSION

MLP-born children have impaired lung function trajectories over the first 5 years of life, highlighting the importance of strengthening maternal health, perinatal care and strategies to reduce tobacco smoke exposure and early life LRTI.