title: Placental villous hypermaturation is associated with idiopathic preterm birth.
abstract: OBJECTIVE
  Pregnancy complications such as intra-amniotic infection, preeclampsia, and fetal intrauterine growth restriction (IUGR) account for most cases of preterm birth (PTB), but many spontaneous PTB cases do not have a clear etiology. We hypothesize that placental insufficiency may be a potential cause of idiopathic PTB.
  
  
  METHODS
  Secondary analysis of 82 placental samples from women with PTB obtained from a multicenter trial of repeat versus single antenatal corticosteroids. Samples were centrally reviewed by a single placental pathologist masked to clinical outcomes. The histopathologic criterion for infection was the presence of acute chorioamnionitis defined as neutrophils marginating into the chorionic plate. Placental villous hypermaturation (PVH) was defined as a predominance of terminal villi (similar to term placenta) with extensive syncytial knotting. Idiopathic PTB comprised a group without another known etiology such as preeclampsia, IUGR or infection.
  
  
  RESULTS
  Acute chorioamnionitis was observed in 33/82 (40%) cases. Other known causes of PTB were reported in 18/82 (22%). The remaining 31/82 (38%) were idiopathic. The frequency of PVH in idiopathic PTB (26/31 = 84%) was similar to cases with IUGR or preeclampsia (16/18 = 89%), but significantly more common than PVH in the group with acute chorioamnionitis (10/33 = 30%) (p < 0.001).
  
  
  CONCLUSIONS
  PVH, which is a histologic marker of relative placental insufficiency, is a common finding in idiopathic PTB.
authors.affiliation: Departments of Pathology and Obstetrics & Gynecology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Mail Code L471, Portland, OR 97239, USA. morgante@ohsu.edu
authors.forename: Terry K
authors.initials: TK
authors.lastname: Morgan
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Tolosa
authors.forename: Lisa
authors.initials: L
authors.lastname: Mele
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Wapner
authors.forename: Catherine Y
authors.initials: CY
authors.lastname: Spong
authors.forename: Yoram
authors.initials: Y
authors.lastname: Sorokin
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Dudley
authors.forename: Alan M
authors.initials: AM
authors.lastname: Peaceman
authors.forename: Brian M
authors.initials: BM
authors.lastname: Mercer
authors.forename: John M
authors.initials: JM
authors.lastname: Thorp
authors.forename: Mary Jo
authors.initials: MJ
authors.lastname: O'Sullivan
authors.forename: Susan M
authors.initials: SM
authors.lastname: Ramin
authors.forename: Dwight J
authors.initials: DJ
authors.lastname: Rouse
authors.forename: Baha
authors.initials: B
authors.lastname: Sibai
mesh_terms: D002821:Chorioamnionitis / Q000473:pathology; D005260:Female; D006801:Humans; D010920:Placenta / Q000473:pathology*; D010927:Placental Insufficiency / Q000473:pathology; D011247:Pregnancy; D047928:Premature Birth / Q000209:etiology* / Q000473:pathology; D012189:Retrospective Studies