Third trimester fetal lung volume, thoracic circumference, and early infant lung function

We aimed to investigate the relationship between fetal third trimester lung volume (LV), thoracic circumference (TC), fetal weight, as well as fetal thoracic and weight growth, and early infant lung function.

Fetal LV, TC and estimated weight were measured with ultrasound at 30 gestational weeks in 257 fetuses from the general population-based prospective cohort study Preventing Atopic Dermatitis and ALLergies in Children (PreventADALL). Fetal thoracic growth rate and weight increase were calculated using TC and estimated fetal weight measured by ultrasound during pregnancy, and TC and birthweight of the newborn. Lung function was assessed by tidal flow-volume measurement in awake infants at 3 months of age. The associations between fetal size (LV, TC, and estimated weight) and growth (thoracic growth rate and fetal weight increase) measures and the time to peak tidal expiratory flow to expiratory time ratio (t_PTEF /t_E ) as well as tidal volume standardized for body weight (V_T /kg) were analyzed using linear and logistic regression models.

We observed no associations between fetal LV, TC or estimated fetal weight and t_PTEF /t_E as a continuous variable, t_PTEF /t_E  < 25th percentile, or V_T /kg. Similarly, fetal thoracic growth and weight increase were not associated with infant lung function. Analyses stratified for sex showed a significant inverse association between fetal weight increase and V_T /kg (p = 0.02) in girls.

Overall, fetal third trimester LV, TC, estimated fetal weight, thoracic growth rate and weight increase were not associated with infant lung function at 3 months of age.