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Timing of delivery in women with pre-pregnancy diabetes mellitus: a population-based study
  1. Meghan Brown1,
  2. Nir Melamed2,
  3. Beth Murray-Davis3,
  4. Haroon Hassan4,
  5. Karizma Mawjee5,
  6. Jon Barrett2,
  7. Sarah D McDonald6,
  8. Joel G Ray7,
  9. Michael Geary8,
  10. Howard Berger5
  1. 1Obstetrics and Gynecology, University of Toronto, Toronto, Ontario, Canada
  2. 2Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
  3. 3Department of Obstetrics and Gynecology, Midwifery Education Program, McMaster University, Hamilton, Ontario, Canada
  4. 4Better Outcomes Registry and Network, Children’s Hospital of Eastern Ontario (CHEO), Toronto, Ontario, Canada
  5. 5Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Unity Health Toronto, Toronto, Ontario, Canada
  6. 6Division of Maternal-Fetal Medicine, Departments of Obstetrics and Gynecology, Radiology and Health Research Methods, Evidence and Impact, McMaster University, Hamilton, Ontario, Canada
  7. 7Departments of Medicine and Obstetrics and Gynaecology, Unity Health Toronto, Toronto, Ontario, Canada
  8. 8Department of Obstetrics & Gynaecology, Rotunda Hospital, Dublin, Ireland
  1. Correspondence to Dr Howard Berger; howard.berger{at}


Objectives Controversy exists about the timing of delivery of women with pre-pregnancy type 1 and 2 diabetes mellitus (PDM). This study aims to compare maternal and neonatal outcomes after induction of labor (IOL) at 38 weeks’ gestation versus expectant management from 39 weeks onward.

Research design and methods This was a retrospective population-based cohort study using data from the Better Outcomes Registry and Network in Ontario Canada. Included were all women with PDM, who had a singleton hospital birth at ≥380/7 weeks’ gestation from 2012 to 2017. Maternal and perinatal outcomes were compared between 937 pregnancies that underwent IOL at 380/7–386/7 weeks (‘38-IOL group’) versus 1276 pregnancies expectantly managed resulting in a birth at ≥390/7 weeks (‘39-Exp group’). The primary outcome was all-cause cesarean delivery. Multivariable modified Poisson regression was performed to generate adjusted relative risks (aRR) and 95% CIs, adjusted for parity, maternal age, pre-pregnancy body mass index and PDM type. Other outcomes included instrumental delivery, neonatal intensive care unit (NICU) admission, and newborn metabolic disturbances.

Results Cesarean delivery occurred in 269 women (28.7%) in the 38-IOL group versus 333 women (26.1%) in the 39-Exp group—aRR 1.07 (95% CI 0.94 to 1.22). The respective rates of instrumental delivery were 11.2% and 10.2% (aRR 1.25, 95% CI 0.98 to 1.61). NICU admission was more common in the 38-IOL group (27.6%) than in the 39-Exp group (16.8%) (aRR 1.61, 95% CI 1.36 to 1.90), as were jaundice requiring phototherapy (12.4% vs 6.2%) (aRR 1.93, 95% CI 1.46 to 2.57) and newborn hypoglycemia (27.3% vs 14.7%) (aRR 1.74, 95% CI 1.46 to 2.07).

Conclusion In pregnant women with PDM, IOL at 380/7–386/7 weeks was not associated with a higher risk of cesarean delivery, compared with expectant management, but was associated with a higher risk of certain adverse neonatal outcomes.

  • pregestational diabetes
  • pregnancy
  • type 1
  • type 2

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  • Contributors MB and HB made substantial contributions to the conception, design, and interpretation of data for the work. NM, BMD, KM, JB, SDM, JGR and MG made substantial contributions to the conception and design of data for the work. HH made substantial contributions to the analysis of data for the work. All authors were involved in drafting the work or revising it critically for important intellectual content, had final approval of the version to be published, and were in agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

  • Funding This work was supported by the Canadian Institute of Health Research (CIHR) (Grant No 146442) and did not include an external peer review for scientific quality; Non-Communicable Diseases in Obstetrics: Improving Quality of Care and Maternal-Infant Outcomes Through an Obstetrical Research Network. Matched funding was provided by the Department of Obstetrics and Gynaecology at the University of Toronto, McMaster University, Sunnybrook Research Institute, and Providence St Joseph’s and St Michael’s Healthcare.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval Ethics approval to conduct this study was obtained from the St Michael’s Hospital Research Ethics Board.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available from the Better Outcomes Registry and Network (

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