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

Young Ju Suh, Ho Kim, Ju Hee Seo, Hyesook Park, Young Ju Kim, Yun Chul Hong, Eun Hee Ha

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


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.

Original languageEnglish
Pages (from-to)613-621
Number of pages9
JournalInternational Archives of Occupational and Environmental Health
Issue number5
StatePublished - 2009

Bibliographical note

Funding Information:
Acknowledgments This study was supported by a Seoul Research & Business Development grant (#2005-1547-1), Republic of Korea.


  • Extended Cox model
  • PM exposure
  • Preterm birth


Dive into the research topics of 'Different effects of PM10 exposure on preterm birth by gestational period estimated from time-dependent survival analyses'. Together they form a unique fingerprint.

Cite this