title: Pre-pregnant body mass index, gestational weight gain and the risk of operative delivery.
abstract: OBJECTIVE
  To estimate the risk of operative delivery according to maternal pre-pregnant body mass index (BMI) and gestational weight gain.
  
  
  METHODS
  Population-based pregnancy cohort study.
  
  
  METHODS
  The Norwegian Mother and Child Cohort Study.
  
  
  METHODS
  Term singleton deliveries in cephalic presentation, excluding preeclampsia, chronic hypertension, diabetes, gestational diabetes and placenta previa (n = 50,416).
  
  
  METHODS
  Relative risks (RR) were obtained using general linear models.
  
  
  METHODS
  RR of operative vaginal delivery and cesarean section.
  
  
  RESULTS
  Overweight and obese women had an increased risk of cesarean section, strongest for women with a pre-pregnancy BMI >40 (RR: 3.4, 95% confidence interval (CI): 2.8-4.1). There was also an increased risk of vacuum extraction delivery for women with a pre-pregnancy BMI >40 (RR: 1.5, 95% CI: 1.04-2.2). Women with a gestational weight gain of ≥16 kg had a significantly increased risk of forceps, vacuum extraction and cesarean section (RR: 1.2, 95% CI: 1.03-1.4, RR: 1.2, 95% CI: 1.1-1.23 and RR: 1.3, 95% CI: 1.26-1.4, respectively). Weight gain during pregnancy was significantly lower in obese women, but the children tended to be larger.
  
  
  CONCLUSIONS
  Obese women have an increased risk of operative delivery with vacuum extraction and cesarean section. Independently of pre-pregnancy BMI, we found an increased risk of operative intervention during delivery for women with gestational weight gain above 16 kg.
authors: Department of Public Health and Primary Health Care, University of Bergen, Bergen, Norway. nils-halvdan.morken@kk.uib.no
authors: Nils-Halvdan
authors: NH
authors: Morken
authors: Kari
authors: K
authors: Klungsøyr
authors: Per
authors: P
authors: Magnus
authors: Rolv
authors: R
authors: Skjærven
mesh_terms: D000328:Adult; D015992:Body Mass Index; D002585:Cesarean Section / Q000706:statistics & numerical data*; D015331:Cohort Studies; D005113:Extraction, Obstetrical / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D016014:Linear Models; D009765:Obesity / Q000503:physiopathology; D050177:Overweight / Q000503:physiopathology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000503:physiopathology; D011446:Prospective Studies; D012306:Risk; D013851:Thinness / Q000503:physiopathology; D015430:Weight Gain