title: Association of extremes of prepregnancy BMI with the clinical presentations of preterm birth.
abstract: OBJECTIVE
  The purpose of this study was to examine associations between the prepregnancy maternal body mass index (BMI) across the 3 clinical presentations of preterm birth (PTB).
  
  
  METHODS
  We conducted a retrospective cohort study of the records of 11,726 women. The World Health Organization International Classification was used to categorize BMI. The primary outcome of the study was PTB (<37 weeks' gestation) presenting as spontaneous preterm labor, preterm premature rupture of the membranes, or a medical indication. We used univariable and multivariable logistic regression analysis to analyze the data (P < .05).
  
  
  RESULTS
  We found (1) a significant increase in the overall incidence of PTB at the extremes of BMI, (2) a higher risk for PTB from spontaneous preterm labor at the lower extremes (low plus moderate thinness) of BMI (adjusted odds ratio [aOR], 2.4; 95% confidence interval [CI], 1.4-4.2; P = .003), (3) a higher risk for preterm premature rupture of the membranes at the upper extremes (obese class II plus III) of BMI (aOR, 1.6; 95% CI, 1.1-2.3; P = .02), and (4) a higher risk for a medically indicated PTB at the lower (aOR, 2.8; 95% CI, 1.4-5.6; P = .004) and upper (aOR, 1.5; 95% CI, 1.1-2.2; P = .02) extreme of BMI.
  
  
  CONCLUSIONS
  Women at the extremes of prepregnancy BMI are at risk for PTB.
authors: Department of Obstetrics and Gynecology, University of Colorado Denver, Aurora, CO.
authors: Anne M
authors: AM
authors: Lynch
authors: Department of Obstetrics and Gynecology, University of Colorado Denver, Aurora, CO.
authors: Jan E
authors: JE
authors: Hart
authors: School of Medicine Case Western Reserve University, Cleveland, OH.
authors: Ogechi C
authors: OC
authors: Agwu
authors: Department of Obstetrics and Gynecology, University of Colorado Denver, Aurora, CO.
authors: Barbra M
authors: BM
authors: Fisher
authors: Colorado School of Public Health, Aurora, CO.
authors: Nancy A
authors: NA
authors: West
authors: Department of Obstetrics and Gynecology, University of Colorado Denver, Aurora, CO.
authors: Ronald S
authors: RS
authors: Gibbs
mesh_terms: D000328:Adult; D015992:Body Mass Index; D005260:Female; D005322:Premature Rupture of Fetal Membranes / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D007752:Obstetric Labor, Premature / Q000453:epidemiology; D011247:Pregnancy; D011256:Pregnancy Outcome; D047928:Premature Birth / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors
keywords: phenotypic; prepregnancy BMI; preterm birth