title: Air Pollutant Exposure Within a Few Days of Delivery and Placental Abruption in Japan.
abstract: Placental abruption is an emergency obstetric complication. Although the etiology of abruption is not fully understood, acute stimuli, such as ischemia and/or inflammation, are associated with rupture of the decidual artery, resulting in placental separation. Ischemia and inflammation are acute biologic effects of air pollution. Using a case-crossover design, we tested the hypothesis that a short-term increase in exposure to air pollutants is a potential trigger of placental abruption.
  
  
  
  We received data for western Japan (Kyushu-Okinawa Districts) from the Japan Perinatal Registry Network database. From 2005 to 2010, 821 singleton pregnant women with placental abruption were identified. We assigned daily concentrations of air pollutants, including nitrogen dioxide (NO2), suspended particulate matter, ozone, and sulfur dioxide (SO2), from the nearest monitoring station to the respective delivery hospital of each woman. Because information on the onset day of abruption was not obtained, we assumed the case day to be 1 day before the day of delivery.
  
  
  
  Exposure to NO2 at 2 days' lag was associated with placental abruption (temperature adjusted odds ratio per 10 ppb increase = 1.4; 95% confidence interval = 1.1, 1.8). The association patterns were similar, when we restricted to participants who delivered by emergency cesarean (1.4, 1.1, 1.9), or who delivered after 35 weeks of gestation (1.4, 1.0, 2.0). There was no association with suspended particulate matter, ozone, or SO2.
  
  
  
  We observed an association between NO2 exposure at 2 days before the day of delivery and placental abruption in pregnant Japanese women.
authors.affiliation: From the aEnvironmental Epidemiology Section, Centre for Health and Environmental Risk Research, National Institute for Environmental Studies, Tsukuba, Japan; bDepartment of Obstetrics and Gynaecology, Kyushu University Hospital, Kyushu University, Fukuoka, Japan; and cDepartment of Obstetrics, Fukuoka Children's Hospital, Fukuoka, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Michikawa
authors.forename: Seiichi
authors.initials: S
authors.lastname: Morokuma
authors.forename: Shin
authors.initials: S
authors.lastname: Yamazaki
authors.forename: Kotaro
authors.initials: K
authors.lastname: Fukushima
authors.forename: Kiyoko
authors.initials: K
authors.lastname: Kato
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nitta
mesh_terms: D000037:Abruptio Placentae / Q000453:epidemiology*; D000328:Adult; D000397:Air Pollution / Q000706:statistics & numerical data*; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D009585:Nitrogen Dioxide; D016017:Odds Ratio; D010126:Ozone; D052638:Particulate Matter; D011247:Pregnancy; D012042:Registries; D013458:Sulfur Dioxide; D013997:Time Factors; D055815:Young Adult
chemical_list: D052638:Particulate Matter; D013458:Sulfur Dioxide; D010126:Ozone; D009585:Nitrogen Dioxide