title: Third- and fourth-degree perineal tears: prevalence and risk factors in the third millennium.
abstract: OBJECTIVE
  We sought to assess the modern prevalence and risk factors for third- and fourth-degree perineal tears.
  
  
  METHODS
  The study population comprised 38,252 women who delivered in one medical center, from January 2005 through December 2009, and met the following inclusion criteria: singleton pregnancy, vertex presentation, and vaginal delivery. Of these, 96 women (0.25%) sustained third- or fourth-degree perineal tears. Maternal and obstetric variables were compared between women with vs without severe perineal tears.
  
  
  RESULTS
  Five variables were found to be statistically significant independent risk factors: Asian ethnicity (odds ratio [OR], 8.9; 95% confidence interval [CI], 4.2-18.9), primiparity (OR, 2.4; 95% CI, 1.5-3.7), persistent occipito posterior (OR, 2.1; 95% CI, 1-4.5), vacuum delivery (OR, 2.7; 95% CI, 1.6-4.6), and heavier birthweight (OR, 1.001; 95% CI, 1-1.001).
  
  
  CONCLUSIONS
  Severe perineal tears are uncommon in modern obstetric practice. Significant risk factors are Asian ethnicity, primiparity, persistent occipito posterior, vacuum delivery, and heavier birthweight.
authors.affiliation: Urogynecology and Pelvic Floor Unit, Department of Obstetrics and Gynecology, Lis Maternity Hospital, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. agroutz@yahoo.com
authors.forename: Asnat
authors.initials: A
authors.lastname: Groutz
authors.forename: Joseph
authors.initials: J
authors.lastname: Hasson
authors.forename: Anat
authors.initials: A
authors.lastname: Wengier
authors.forename: Ronen
authors.initials: R
authors.lastname: Gold
authors.forename: Avital
authors.initials: A
authors.lastname: Skornick-Rapaport
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Lessing
authors.forename: David
authors.initials: D
authors.lastname: Gordon
mesh_terms: D000328:Adult; D044466:Asian People / Q000706:statistics & numerical data; D001724:Birth Weight; D036861:Delivery, Obstetric / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D015601:Injury Severity Score; D007746:Labor Presentation; D022125:Lacerations / Q000145:classification / Q000453:epidemiology* / Q000209:etiology; D015999:Multivariate Analysis; D010298:Parity; D010502:Perineum / Q000293:injuries*; D011247:Pregnancy; D015995:Prevalence; D012307:Risk Factors; D014620:Vacuum Extraction, Obstetrical / Q000009:adverse effects