title: Placenta previa: obstetric risk factors and pregnancy outcome.
abstract: OBJECTIVE
  To determine the incidence, obstetric risk factors and perinatal outcome of placenta previa.
  
  
  METHODS
  All singleton deliveries at our institution between 1990 and 1998 complicated with placenta previa were compared with those without placenta previa.
  
  
  RESULTS
  Placenta previa complicated 0.38% (n = 298) of all singleton deliveries (n = 78 524). A back-step multiple logistic regression model found the following factors to be independently correlated with the occurrence of placenta previa: maternal age above 40 years (OR 3.1, 95% CI 2.0-4.9), infertility treatments (OR 3.1, 95% CI 1.8-5.6), a previous Cesarean section (OR 1.8, 95% CI 1.4-2.4), a history of habitual abortions (OR 1.3, 95% CI 1.3-2.7) and Jewish ethnicity (OR 1.3, 95% CI 1.1-1.8). Pregnancies complicated with placenta previa had significantly higher rates of second-trimester bleeding (OR 156.0, 95% CI 87.2-277.5), pathological presentations (OR 7.6, 95% CI 5.7-10.1), abruptio placentae (OR 13.1, 95% CI 8.2-20.7), congenital malformations (OR 2.6, 95% CI 1.5-4.2), perinatal mortality (OR 2.6, 95% CI 1.1-5.6), Cesarean delivery (OR 57.4, 95% CI 40.7-81.4), Apgar scores at 5 min lower than 7 (OR 4.4, 95% CI 2.3-8.3), placenta accreta (OR 3.6, 95% CI 1.1-9.9) postpartum hemorrhage (OR 3.8, 95% CI 1.2-10.5), postpartum anemia (OR 5.5, 95% CI 4.4-6.9) and delayed maternal and infant discharge from the hospital (OR 10.9, 95% CI 7.3-16.1) as compared to pregnancies without placenta previa. In a multivariable analysis investigating risk factors for perinatal mortality, the following were found to be independent significant factors: congenital malformations, placental abruption, pathological presentations and preterm delivery. In contrast, placenta previa and Cesarean section were found to be protective factors against the occurrence of perinatal mortality while controlling for confounders.
  
  
  CONCLUSIONS
  Although an abnormal implantation per se was not an independent risk factor for perinatal mortality, placenta previa should be considered as a marker for possible obstetric complications. Hence, the detection of placenta previa should encourage a careful evaluation with timely delivery in order to reduce the associated maternal and perinatal complications.
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Health Sciences, Soroka University Medical Center, Ben Gurion University of the Negev, Beer-Sheva, Israel. sheiner@bgumail.bgu.ac.il
authors.forename: E
authors.initials: E
authors.lastname: Sheiner
authors.forename: I
authors.initials: I
authors.lastname: Shoham-Vardi
authors.forename: M
authors.initials: M
authors.lastname: Hallak
authors.forename: R
authors.initials: R
authors.lastname: Hershkowitz
authors.forename: M
authors.initials: M
authors.lastname: Katz
authors.forename: M
authors.initials: M
authors.lastname: Mazor
mesh_terms: D000026:Abortion, Habitual; D000328:Adult; D000367:Age Factors; D018912:Arabs / Q000706:statistics & numerical data; D002585:Cesarean Section; D005260:Female; D006801:Humans; D015994:Incidence; D007557:Israel / Q000453:epidemiology; D007585:Jews / Q000706:statistics & numerical data; D016015:Logistic Models; D008423:Maternal Age; D008499:Medical Records; D016017:Odds Ratio; D010923:Placenta Previa / Q000453:epidemiology* / Q000208:ethnology / Q000209:etiology*; D011247:Pregnancy; D011256:Pregnancy Outcome; D018566:Pregnancy, High-Risk; D012189:Retrospective Studies; D012307:Risk Factors