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Outcomes of elective induction of labour compared with expectant management: population based study

BMJ 2012; 344 doi: https://doi.org/10.1136/bmj.e2838 (Published 10 May 2012) Cite this as: BMJ 2012;344:e2838
  1. Sarah J Stock, clinical lecturer and subspecialty trainee in maternal fetal medicine1,
  2. Evelyn Ferguson, consultant obstetrician2,
  3. Andrew Duffy, information analyst3,
  4. Ian Ford, professor of biostatistics4,
  5. James Chalmers, consultant in public health medicine3,
  6. Jane E Norman, professor of maternal and fetal health1
  1. 1Tommy’s Centre for Maternal and Fetal Health, MRC Centre for Reproductive Health, University of Edinburgh, Queen’s Medical Research Institute, Edinburgh EH16 4SA, UK
  2. 2NHS Lanarkshire, Wishaw General Hospital, Wishaw, UK
  3. 3Information Services Division, NHS National Services Scotland, Edinburgh
  4. 4University of Glasgow Robertson Centre for Biostatistics, Glasgow, UK
  1. Correspondence to: S J Stock sarah.stock{at}ed.ac.uk
  • Accepted 22 March 2012

Abstract

Objective To determine neonatal outcomes (perinatal mortality and special care unit admission) and maternal outcomes (mode of delivery, delivery complications) of elective induction of labour compared with expectant management.

Design Retrospective cohort study using an unselected population database.

Setting Consultant and midwife led obstetric units in Scotland 1981-2007.

Participants 1 271 549 women with singleton pregnancies of 37 weeks or more gestation.

Interventions Outcomes of elective induction of labour (induction of labour with no recognised medical indication) at 37, 38, 39, 40, and 41 weeks’ gestation compared with those of expectant management (continuation of pregnancy to either spontaneous labour, induction of labour or caesarean section at a later gestation).

Main outcome measures Extended perinatal mortality, mode of delivery, postpartum haemorrhage, obstetric anal sphincter injury, and admission to a neonatal or special care baby unit. Outcomes were adjusted for age at delivery, parity, year of birth, birth weight, deprivation category, and, where appropriate, mode of delivery.

Results At each gestation between 37 and 41 completed weeks, elective induction of labour was associated with a decreased odds of perinatal mortality compared with expectant management (at 40 weeks’ gestation 0.08% (37/44 764) in the induction of labour group versus 0.18% (627/350 643) in the expectant management group; adjusted odds ratio 0.39, 99% confidence interval 0.24 to 0.63), without a reduction in the odds of spontaneous vertex delivery (at 40 weeks’ gestation 79.9% (35 775/44 778) in the induction of labour group versus 73.7% (258 665/350 791) in the expectant management group; adjusted odds ratio 1.26, 1.22 to 1.31). Admission to a neonatal unit was, however, increased in association with elective induction of labour at all gestations before 41 weeks (at 40 weeks’ gestation 8.0% (3605/44 778) in the induction of labour group compared with 7.3% (25 572/350 791) in the expectant management group; adjusted odds ratio 1.14, 1.09 to 1.20).

Conclusion Although residual confounding may remain, our findings indicate that elective induction of labour at term gestation can reduce perinatal mortality in developed countries without increasing the risk of operative delivery.

Footnotes

  • Contributors: EF, JEN, and JC conceived the study and obtained funding. SJS, EF, JC, IF, and JEN designed the study and wrote the protocol. AD acquired the data. AD, SJS, JEN, and IF analysed and interpreted the data. The manuscript was drafted by SJS, with all other authors critically revising the paper. JEN is guarantor of the study. All authors had full access to all of the data (including statistical reports and tables) in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis.

  • Funding: This study was funded by research grant CZG/2/292 from the Chief Scientist Office of the Scottish Government Health Directorate. A report was submitted to the funders following completion of the study and peer reviewed. The funders had no role in study design, data collection or analysis, or the decision to publish.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; and no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: Record linkage was approved by the Privacy Advisory Committee of the Information and Statistics Division of the National Health Service Scotland.

  • Data sharing: The anonymised dataset is available from andrew.duffy{at}nhs.net. Consent was not obtained but the presented data are anonymised and risk of identification is low.

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