title: Risk factors of early spontaneous abortions among Japanese: a matched case-control study.
abstract: BACKGROUND
  No epidemiological studies have examined risk factors for early spontaneous abortions among Japanese women. In this matched case-control study, we investigated the associations of reproductive, physical, and lifestyle characteristics of women and their husbands with early spontaneous abortion <12 weeks of gestation.
  
  
  METHODS
  Information was collected through medical records for 430 cases of early spontaneous abortion and 860 controls of term delivery. Two controls were individual-matched to one case according to maternal age (± 3 years) and calendar year of events (either early spontaneous abortion or delivery). Multivariable conditional odds ratios (ORs) and 95% confidence interval (CI) were calculated with conditional logistic-regression.
  
  
  RESULTS
  The risk of early spontaneous abortions was higher for women with a past history of early spontaneous abortions; OR was 1.98 (95% CI: 1.35, 2.89) for one previous spontaneous abortion, 2.36 (95% CI: 1.47, 3.79) for two, and 8.73 (95% CI: 5.22, 14.62) for three or more. Other factors also influence risk; an OR of 2.39 (95% CI: 1.26, 4.25) was found for women who smoked, and 1.65 (95%CI: 1.17, 2.35) for women working outside the home.
  
  
  CONCLUSIONS
  Our finding suggests that for Japanese women, smoking and working may be important public health issue targets for the prevention of early spontaneous abortions.
authors.affiliation: Public Health, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Baba
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Noda
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nakayama
authors.forename: Masako
authors.initials: M
authors.lastname: Waguri
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Mitsuda
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Iso
mesh_terms: D000028:Abortion, Induced / Q000009:adverse effects; D000022:Abortion, Spontaneous / Q000209:etiology*; D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008423:Maternal Age; D008875:Middle Aged; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D014931:Women, Working / Q000706:statistics & numerical data