title: Cohort study of the incidence of spontaneous preterm birth and septic abortion referred by pathological examination in Gifu prefecture in Japan.
abstract: To clarify the incidence of spontaneous preterm birth (PB) and septic abortion (sab) in Gifu prefecture in Japan.
  
  
  
  This prospective, population-based cohort study was approved by our hospital's Institutional Review Board. All 36 hospitals (100%) in Gifu prefecture offering obstetrical services participated in the study. Patient enrollment criteria were: sab and PB from 22 to <37weeks gestation (WG), excluding for maternal and fetal indications. Pathological examinations before 36 WG and associated factors for both PB and chorioamnionitis (CAM) stage 3 were analyzed by multiple logistic regression analysis judging from minimum daily clinical information in Gifu prefecture.
  
  
  
  The sab rate per all deliveries was 29/16871 (0.17%) at 16.9±2.9 WG. The total spontaneous PB rate was 615/16871 (3.65%) at 34.5±2.7 WG, with birth weight (BW) 2267±557g. There were 26 (0.15%) PBs from 22+0 to 27+6 WG (weeks+days) at 25.2±1.5 WG, with BW 745±199g. Among 214 pathological examinations, CAM was detected in 80% (sab) and 63% (PB<36 WG), respectively. Funisitis were 14% and 17% respectively. Episodes of serial genital bleeding and/or hematoma at <12 WG were more frequent in sab and earlier PB (<28 WG) associated with CAM stage 3 (odds 1.9, P<0.0001). Combined factors such as bleeding and past history of CAM correlated with earlier delivery at 23.4±5.9 WG (P=0.0032).
  
  
  
  In Gifu prefecture, the incidence of sab was 0.17% (per all deliveries) and 3.65% of spontaneous PB. The combined risk of past CAM history and bleeding was associated with earlier delivery among total preterm birth.
authors.affiliation: Gifu Preterm Birth Study Group, Japan; Nagara Medical Center, Gifu, Japan. Electronic address: yuichiro@nagara-lan.hosp.go.jp.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Takahashi
authors.affiliation: Gifu Preterm Birth Study Group, Japan; Nagara Medical Center, Gifu, Japan.
authors.forename: Shigenori
authors.initials: S
authors.lastname: Iwagaki
authors.affiliation: Gifu Preterm Birth Study Group, Japan; Ohgaki Municipal Hospital, Gifu, Japan.
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Itoh
authors.affiliation: Gifu Preterm Birth Study Group, Japan; Tajimi Hospital, Gifu, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Nakamura
authors.affiliation: Gifu Preterm Birth Study Group, Japan; Takayama red-cross hospital, Gifu, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kuwabara
authors.affiliation: Gifu Preterm Birth Study Group, Japan; Gifu Municipal Hospital, Gifu, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Hiraku
authors.affiliation: Gifu Preterm Birth Study Group, Japan; Tokai central hospital, Gifu, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Hori
authors.affiliation: Gifu Preterm Birth Study Group, Japan; Misao Ladies Hospital, Gifu, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Misao
authors.affiliation: Gifu Preterm Birth Study Group, Japan; Gifu University Hospital, Gifu, Japan.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Furui
authors.affiliation: Gifu Preterm Birth Study Group, Japan; Gifu University Hospital, Gifu, Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Morishige
mesh_terms: D000031:Abortion, Septic / Q000453:epidemiology* / Q000473:pathology; D005260:Female; D006801:Humans; D015994:Incidence; D007564:Japan; D011247:Pregnancy; D047928:Premature Birth / Q000453:epidemiology* / Q000473:pathology
keywords: Chorioamnionitis; Cohort study; Funisitis; Pathological examination; Septic abortion; Spontaneous preterm birth