title: Pre-pregnancy Body Mass Index (BMI) and delivery outcomes in a Canadian population.
abstract: BACKGROUND
  Worldwide there has been a dramatic increase in the prevalence of overweight and obesity in women of childbearing age. Growing evidence suggests that maternal overweight and obesity is associated with poor maternal and perinatal outcomes. This study evaluated the impact of maternal pre-pregnancy overweight and obesity on pregnancy, labour and delivery outcomes in a cohort of women with term, singleton pregnancies cared for by family physicians in community based practices.
  
  
  METHODS
  This study is a secondary analysis of the All Our Babies Cohort, a prospective, community-based pregnancy cohort in Calgary, Alberta. Maternal self-reported data on height and pre-pregnancy weight from term, singleton, cephalic pregnancies (n = 1996) were linked to clinical data on pregnancy and birth events retrieved from electronic health records. Descriptive and bivariate regression analysis were used to compare pregnancy and birth outcomes between women categorized as normal weight, overweight and obese based on the pre-pregnancy BMI. Multinomial regression analysis stratified by type of labour onset examined the association between pre-pregnancy BMI and mode of delivery controlling for maternal age, pre-existent health conditions, parity, fertility treatments, history of C-section and pregnancy complications.
  
  
  RESULTS
  The cohort consisted of 65.8% normal weight, 23.6% overweight and 10.6% obese women. Women with increased pre-pregnancy BMI were more likely to develop pregnancy complications such as preeclampsia (OR 3.5, CI 2.0-4.6 for overweight; OR 5.3, CI 3.3-8.5 for obese) and gestational diabetes (OR 3.0, CI 1.8-5.0 for overweight; OR 6.5, CI 3.7-11.2 for obese) than normal weight women. Spontaneous onset of labour was recorded in 71.2% of women with normal pre-pregnancy BMI, whereas 39.3% of overweight and 49% of obese women had their labour induced. For women with spontaneous labour, pre-pregnancy BMI was not a significant risk factor for mode of delivery, controlling for covariates. Among women with induced labor, obesity was a significant risk factor for delivery by C-section (adjusted OR 2.2; CI 1.2-4.1).
  
  
  CONCLUSIONS
  Even among women with term, singleton pregnancies obtaining prenatal care in community-based settings, obese women who undergo labour induction are at increased risk of obstetrical interventions at delivery. These findings highlight the importance of tailored maternal care in pregnancy and at delivery of pregnant women with increased BMI in order to improve the outcomes and wellbeing of these women and their children.
authors.affiliation: Departments of Paediatrics/Physiology & Pharmacology, Cumming School of Medicine, Alberta Centre for Child, Family & Community Research - Child Development Centre, University of Calgary, c/o 2888 Shaganappi Trail NW, Calgary, AB, T3B 6A8, Canada. aevintur@ucalgary.ca.
authors.forename: Angela
authors.initials: A
authors.lastname: Vinturache
authors.affiliation: Faculty of Medicine, University of Alberta, 2J 2.00 WC Mackenzie Health Science Centre, Edmonton, AB, T6G 2R7, Canada. moledina@ualberta.ca.
authors.forename: Nadia
authors.initials: N
authors.lastname: Moledina
authors.affiliation: Department of Pediatrics, Cumming School of Medicine, Alberta Centre for Child, Family & Community Research - Child Development Centre, University of Calgary, c/o 2888 Shaganappi Trail NW, Calgary, AB, T3B 6A8, Canada. SMD@albertahealthservices.ca.
authors.forename: Sheila
authors.initials: S
authors.lastname: McDonald
authors.affiliation: Department of Physiology & Pharmacology, Cumming School of Medicine, University of Calgary, # 277 HRMB Building, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada. dmslater@ucalgary.ca.
authors.forename: Donna
authors.initials: D
authors.lastname: Slater
authors.affiliation: Departments of Pediatrics and Community Health Sciences, Cumming School of Medicine, Alberta Centre for Child, Family & Community Research, Child Development Centre, University of Calgary, c/o 2888 Shaganappi Trail NW, Calgary, AB, T3B 6A8, Canada. Suzanne.Tough@albertahealthservices.ca.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Tough
mesh_terms: D000293:Adolescent; D000328:Adult; D000416:Alberta / Q000453:epidemiology; D015992:Body Mass Index; D002585:Cesarean Section / Q000706:statistics & numerical data; D016640:Diabetes, Gestational / Q000453:epidemiology*; D005260:Female; D006801:Humans; D056865:Ideal Body Weight; D007745:Labor Onset; D007751:Labor, Induced / Q000706:statistics & numerical data; D009765:Obesity / Q000150:complications / Q000453:epidemiology*; D050177:Overweight / Q000150:complications / Q000453:epidemiology; D011225:Pre-Eclampsia / Q000453:epidemiology*; D011247:Pregnancy; D011446:Prospective Studies; D012307:Risk Factors; D055815:Young Adult