Prenatal nitrate air pollution exposure and reduced child lung function: Timing and fetal sex effects.

BACKGROUND

Prenatal particulate air pollution exposure may alter lung growth and development in utero in a time-sensitive and sex-specific manner, resulting in reduced lung function in childhood. Such relationships have not been examined for nitrate (NO).

METHODS

We implemented Bayesian distributed lag interaction models (BDLIMs) to identify sensitive prenatal windows for the influence of NO on lung function at age 7 years, assessing effect modification by fetal sex. Analyses included 191 mother-child dyads. Daily ambient NO exposure over pregnancy was estimated using a hybrid chemical transport (Geos-Chem)/land-use regression model. Spirometry was performed at mean (SD) age of 6.99 (0.89) years, with forced expiratory volume in one second (FEV) and forced vital capacity (FVC) z-scores accounting for child age, sex, height and race/ethnicity.

RESULTS

Most mothers were Hispanic (65%) or Black (22%), had ≤ high school education (67%), and never smoked (71%); 17% children had asthma. BDILMs adjusted for maternal age and education and child's asthma identified an early sensitive window of 6-12 weeks gestation, during which increased NO was significantly associated with reduced FEV z-scores specifically among boys. BDLIM analyses demonstrated similar sex-specific patterns for FVC.

CONCLUSION

Early gestational NO exposure is associated with reduced child lung function, especially in boys.