title: Predictors of severe perineal lacerations in Chinese women.
abstract: OBJECTIVE
  Chinese women have been shown to have a higher incidence of severe perineal laceration compared to other ethnic groups. We sought to test the hypothesis that this risk is related to body mass index (BMI) or to a relative fetal-maternal size disproportion as measured by the ratio of the newborn birthweight to maternal BMI (BW:BMI).
  
  
  METHODS
  A retrospective cohort study was performed using a pre-existing obstetric database. Third- and fourth-degree perineal lacerations served as the primary outcome of interest. Logistic regression was used to compare Chinese women to other ethnic groups and adjust for confounders.
  
  
  RESULTS
  Three thousand and eighty-five singleton vaginal deliveries were identified, with BMI data available for 2281. Chinese women had a greater risk for severe perineal laceration compared to Caucasian (OR: 3.22; 95% CI: 0.73-14.32) and Hispanic women (OR: 2.88; 95% CI: 1.92-4.30). Multivariate analysis found that newborn birth weight plays a role (OR: 1.0012; 95% CI: 1.0007-1.0016), but BMI alone did not explain the discrepancy (P=0.89). However, the BW:BMI ratio appears to be a stronger predictor of laceration rate than either variable alone (OR: 1.011; 95% CI: 1.003-1.020).
  
  
  CONCLUSIONS
  The higher risk of severe perineal laceration in Chinese women compared to other ethnicities can be attributed, in part, to a relative fetal-maternal size disproportion.
authors.affiliation: Department of Obstetrics and Gynecology, New York University School of Medicine, New York, NY, USA. nadavmd@hotmail.com
authors.forename: Nadav
authors.initials: N
authors.lastname: Schwartz
authors.forename: David E
authors.initials: DE
authors.lastname: Seubert
authors.forename: Julian
authors.initials: J
authors.lastname: Mierlak
authors.forename: Alan A
authors.initials: AA
authors.lastname: Arslan
mesh_terms: D000328:Adult; D001724:Birth Weight; D015992:Body Mass Index; D002681:China / Q000208:ethnology; D015331:Cohort Studies; D036861:Delivery, Obstetric / Q000379:methods; D005260:Female; D005865:Gestational Age; D006630:Hispanic or Latino; D006801:Humans; D007744:Obstetric Labor Complications / Q000453:epidemiology / Q000208:ethnology*; D010298:Parity; D036801:Parturition; D010502:Perineum / Q000293:injuries*; D011247:Pregnancy; D012189:Retrospective Studies