title: Induction of labor before 40 weeks is associated with lower rate of cesarean delivery in women with gestational diabetes mellitus.
abstract: BACKGROUND
  In women with gestational diabetes mellitus, it is not clear whether routine induction of labor at <40 weeks of gestation is beneficial to mother and newborn infant.
  
  
  OBJECTIVE
  The purpose of this study was to compare outcomes among women with gestational diabetes mellitus who had induction of labor at either 38 or 39 weeks with those whose pregnancy was managed expectantly.
  
  
  METHODS
  We included all women in Ontario, Canada, with diagnosed gestational diabetes mellitus who had a singleton hospital birth at ≥38 + 0 weeks of gestation between April 2012 and March 2014. Data were obtained from the Better Outcomes Registry & Network Ontario, which is a province-wide registry of all births in Ontario, Canada. Women who underwent induction of labor at 38 + 0 to 38 + 6 weeks of gestation (38-IOL; n = 1188) were compared with those who remained undelivered until 39 + 0 weeks of gestation (38-Expectant; n = 5229). Separately, those women who underwent induction of labor at 39 + 0 to 39 + 6 weeks of gestation (39-IOL; n = 1036) were compared with women who remained undelivered until 40 + 0 weeks of gestation (39-Expectant; n = 2162). Odds ratios and 95% confidence intervals were adjusted for maternal age, parity, insulin treatment, and prepregnancy body mass index.
  
  
  RESULTS
  Of 281,480 women who gave birth during the study period, 14,600 women (5.2%) had gestational diabetes mellitus; of these, 8392 women (57.5%) met all inclusion criteria. Compared with the 38-Expectant group, those women in the 38-IOL group had lower odds for cesarean delivery (adjusted odds ratio, 0.73; 95% confidence interval, 0.52-0.90), higher odds for neonatal intensive care unit admission (adjusted odds ratio, 1.36; 95% confidence interval, 1.09-1.69), and no difference in other maternal-newborn infant outcomes. Compared with the 39-Expectant group, women in the 39-IOL group likewise had lower odds for cesarean delivery (adjusted odds ratio, 0.73; 95% confidence interval, 0.58-0.93) but no difference in neonatal intensive care unit admission (adjusted odds ratio, 0.83; 95% confidence interval, 0.61-1.11).
  
  
  CONCLUSIONS
  In women with gestational diabetes mellitus, the routine induction of labor at 38 or 39 weeks is associated with a lower risk of cesarean delivery compared with expectant management but may increase the risk of neonatal intensive care unit admission when done at <39 weeks of gestation.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Sunnybrook Health Sciences Centre, St. Michael's Hospital, University of Toronto, Ontario, Canada. Electronic address: nir.melamed@sunnybrook.ca.
authors.forename: Nir
authors.initials: N
authors.lastname: Melamed
authors.affiliation: Departments of Medicine and Obstetrics and Gynecology, St. Michael's Hospital, University of Toronto, Ontario, Canada.
authors.forename: Joel G
authors.initials: JG
authors.lastname: Ray
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, St. Michael's Hospital, University of Toronto, Ontario, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Geary
authors.affiliation: Better Outcomes Registry & Network Ontario, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.
authors.forename: Daniel
authors.initials: D
authors.lastname: Bedard
authors.affiliation: Better Outcomes Registry & Network Ontario, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.
authors.forename: Cathy
authors.initials: C
authors.lastname: Yang
authors.affiliation: Better Outcomes Registry & Network Ontario, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada.
authors.forename: Ann
authors.initials: A
authors.lastname: Sprague
authors.affiliation: Division of Midwifery, Department of Obstetrics and Gynecology, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Beth
authors.initials: B
authors.lastname: Murray-Davis
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Sunnybrook Health Sciences Centre, St. Michael's Hospital, University of Toronto, Ontario, Canada.
authors.forename: Jon
authors.initials: J
authors.lastname: Barrett
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, St. Michael's Hospital, University of Toronto, Ontario, Canada.
authors.forename: Howard
authors.initials: H
authors.lastname: Berger
mesh_terms: D000328:Adult; D002585:Cesarean Section / Q000706:statistics & numerical data*; D016640:Diabetes, Gestational; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal / Q000706:statistics & numerical data; D007751:Labor, Induced / Q000379:methods*; D016015:Logistic Models; D015999:Multivariate Analysis; D016017:Odds Ratio; D009864:Ontario; D017063:Outcome Assessment, Health Care; D010343:Patient Admission / Q000706:statistics & numerical data; D011247:Pregnancy; D012189:Retrospective Studies
keywords: delivery; expectant management; gestational diabetes mellitus; induction