title: Incidence and risk factors for recurrent spontaneous preterm birth: A retrospective cohort study in Japan.
abstract: OBJECTIVE
  The aim of this study was to assess the incidence and risk factors for recurrent spontaneous preterm birth (PTB) in Japan.
  
  
  METHODS
  A retrospective cohort study was conducted at five tertiary perinatal centers in Osaka, Japan from 2008 through 2012. Perinatal data were collected from medical records of women with a singleton gestation and a previous spontaneous PTB. Exclusion criteria were first-trimester spontaneous abortion, first antenatal visit beyond 14 weeks of gestation, and previous PTB with medical indications, placenta previa, abruptio placenta, multiple pregnancy, fetal anomaly, and antepartum fetal demise. The associations between recurrent spontaneous PTB and perinatal factors were evaluated by logistic regression analysis.
  
  
  RESULTS
  Of 547 women with a previous spontaneous PTB, 89 (16.3%) suffered a recurrent spontaneous PTB. The risk factors for recurrence included multiple previous spontaneous PTB (adjusted odds ratio [aOR]: 2.26; 95% confidence interval [CI]: 1.19-4.30; P = 0.013), no previous term birth (aOR: 2.08; 95%CI: 1.24-3.49; P = 0.005), and interpregnancy interval < 12 months (aOR: 2.13; 95%CI: 1.17-3.85; P = 0.013).
  
  
  CONCLUSIONS
  Approximately one in six women with a previous spontaneous PTB suffered a recurrent spontaneous PTB. Multiple previous spontaneous PTB, no previous term birth, and short interpregnancy interval were independent risk factors for recurrence.
authors: Department of Maternal-Fetal Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health.|Department of Obstetrics and Gynecology, Osaka University.
authors: Michiko
authors: M
authors: Yamashita
authors: Department of Maternal-Fetal Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health.
authors: Shusaku
authors: S
authors: Hayashi
authors: Department of Obstetrics and Gynecology, Osaka University.
authors: Masayuki
authors: M
authors: Endo
authors: Department of Obstetrics and Gynecology, Aizenbashi Hospital.
authors: Kentaro
authors: K
authors: Okuno
authors: Department of Obstetrics and Gynecology, Rinku General Medical Center, Osaka.
authors: On
authors: O
authors: Fukui
authors: Department of Obstetrics and Gynecology, Osaka University.
authors: Kazuya
authors: K
authors: Mimura
authors: Department of Obstetrics and Gynecology, Hyogo Prefectural Nishinomiya Hospital, Hyogo, Japan.
authors: Yosuke
authors: Y
authors: Tachibana
authors: Department of Maternal-Fetal Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health.
authors: Keisuke
authors: K
authors: Ishii
authors: Department of Maternal-Fetal Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health.
authors: Nobuaki
authors: N
authors: Mitsuda
authors: Department of Obstetrics and Gynecology, Osaka University.
authors: Tadashi
authors: T
authors: Kimura
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007564:Japan; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology* / Q000209:etiology; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors
keywords: interpregnancy interval; obstetric history; racial disparity; recurrence; spontaneous preterm birth