Original Article

International Archives of Occupational and Environmental Health

, Volume 82, Issue 5, pp 613-621

First online:

Different effects of PM10 exposure on preterm birth by gestational period estimated from time-dependent survival analyses

  • Young Ju SuhAffiliated withCenter for Genome Research, Samsung Biomedical Research Institute
  • , Ho KimAffiliated withDepartment of Epidemiology and Biostatistics, School of Public Health and the Institute of Environment and Health, Seoul National University Email author 
  • , Ju Hee SeoAffiliated withDepartment of Preventive Medicine, Ewha Medical Research Institute, School of Medicine, Ewha Womans UniversityBK21 Research Division for Medicine, School of Medicine, Ewha Womans University
  • , Hyesook ParkAffiliated withDepartment of Preventive Medicine, Ewha Medical Research Institute, School of Medicine, Ewha Womans UniversityBK21 Research Division for Medicine, School of Medicine, Ewha Womans University
  • , Young Ju KimAffiliated withDepartment of Obstetrics and Gynecology, School of Medicine, Ewha Womans University
  • , Yun Chul HongAffiliated withDepartment of Preventive Medicine, College of Medicine, Seoul National University
  • , Eun Hee HaAffiliated withDepartment of Preventive Medicine, Ewha Medical Research Institute, School of Medicine, Ewha Womans UniversityBK21 Research Division for Medicine, School of Medicine, Ewha Womans University Email author 

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Abstract

Purpose

We conducted this study to determine if the preterm risks due to PM10 exposure vary with the exposure periods during pregnancy. This study was also conducted to estimate the different effects of PM10 exposure on preterm birth by exposure periods using the extended Cox model with PM10 exposure as a time-dependent covariate.

Methods

We studied birth data obtained from the Korea National Statistical office for 374,167 subjects who were delivered between 1998 and 2000 in Seoul, South Korea. We used PM10 data that was measured hourly to give 24-h averages at 27 monitoring stations in Seoul. The extended Cox model with time-dependent exposure was used to determine if the risk of preterm delivery could be associated with PM10 exposures for each trimester during pregnancy.

Results

Effect of PM10 exposure prior to the 37 weeks of gestational period was stronger on the risk of premature birth than that posterior to the 37 weeks of gestational weeks. This trend was consistent for each trimester; however, the hazard ratios for preterm delivery associated with PM10 exposure in the first and third trimester were slightly higher than those of the second trimester.

Conclusions

The risk of preterm birth associated with exposure to PM10 differed with the exposure period of the neonates. Therefore, when studying the impact of air pollution exposure during pregnancy, the exposure period during pregnancy should be considered.

Keywords

Preterm birth PM10 exposure Extended Cox model