The Associations between Exposure to Fine Particulate Matters during Pregnancy and natal Period and Asthma Onset in a Metropolitan Area in Taiwan

摘要

Background/Aim The development of lung is a multi-stage process from conception to early postnatal period, any disruption of the process by pollutants may trigger respiratory morbidity later. Exposure to particulate matters (PM) during both prenatal and postnatal periods may be associated with the increased risk of asthma. We aimed to evaluate the effects of weekly average PM with aerodynamic diameter less than 2.5μm (PM2.5) during prenatal and early postnatal periods on asthma and tried to find out the most vulnerable time windows of asthma that would help to elucidate the possible mechanism for effects of PM2.5 on asthma. Methods A birth cohort study including 184,604 neonates born during 2004-2011 in Taichung city was retrieved from Taiwan Maternal and Child Health Database and followed up until 2014. A highly temporal resolution satellite-based hybrid model has been applied to estimate daily PM2.5 for each subject. A Cox proportional hazard model combined with the distributed lag non-linear model was performed to evaluate the associations of asthma with weekly average exposure to PM2.5 during prenatal and early postnatal period. Results Within the birth cohort, there were total 34,336 asthma cases (18.60%), the mean age of infants who received asthma diagnosis was 3.39±1.78 years. The results reveal that increased exposure to PM2.5 during 3-6 gestational weeks, 25-36 gestational weeks and during 10-50 weeks after birth were significantly associated with increased incident asthma. Additionally, we observed consistent positive associations of asthma with exposure to PM2.5 during the prenatal and postnatal period for both males and females. Conclusion Our findings added evidence into the growing literature that both prenatal and postnatal exposures to PM2.5 are associated with the later development of asthma. The vulnerable time windows may be within early and late gestation that showed a bimodal pattern. Further studies are needed to confirm the vulnerable time windows.