Elective induction of labour and expectant management in late-term pregnancy: A prospective cohort study alongside the INDEX randomised controlled trial

Aafke Bruinsma*, Judit KJ Keulen, Joep C. Kortekaas, Jeroen van Dillen, Ruben G. Duijnhoven, Patrick MM Bossuyt, Anton H. van Kaam, Joris AM van der Post, Ben W. Mol, Esteriek de Miranda

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Objective: To assess adverse perinatal outcomes and caesarean section of low-risk women receiving elective induction of labour at 41 weeks or expectant management until 42 weeks according to their preferred and actual management strategy. 

Design: Multicentre prospective cohort study alongside RCT. Setting: 90 midwifery practices and 12 hospitals in the Netherlands. 

Population: 3642 low-risk women with uncomplicated singleton late-term pregnancy. 

Main outcome measures: Composite adverse outcome (perinatal death, Apgar score 5′ < 7, NICU admission, meconium aspiration syndrome), composite severe adverse perinatal outcome (all above with Apgar score 5′ < 4 instead of < 7) and caesarean section. 

Results: From 2012–2016, 3642 women out of 6088 eligible women for the INDEX RCT, participated in the cohort study for observational data collection (induction of labour n = 372; expectant management n = 2174; unknown preference/management strategy n = 1096). Adverse perinatal outcome occurred in 1.1 % (4/372) in the induction group versus 1.9 % (42/2174) in the expectant group (adjRR 0.56; 95 %CI: 0.17–1.79), with severe adverse perinatal outcome occurring in 0.3 % (1/372) versus 1.0 % (22/2174), respectively (adjRR 0.39; 95 % CI: 0.05–2.88). There were no stillbirths among all 3642 women; one neonatal death occurred in the unknown preference/management group. Caesarean section rates were 10.5 % (39/372) after induction and 8.9 % (193/2174) after expectant management (adjRR 1.32; 95 % CI: 0.95–1.84). A higher incidence of adverse perinatal outcome was observed in nulliparous compared to multiparous women. Nulliparous 1.8 % (3/170) in the induction group versus 2.6 % (30/1134) in the expectant management group (adjRR 0.58; 95 % CI 0.14–2.41), multiparous 0.5 % (1/201) versus 1.1 % (11/1039) (adjRR 0.54; 95 % CI 0.07–24.19). One maternal death due to amniotic fluid embolism occurred after elective induction at 41 weeks + 6 days. 

Conclusion: In this cohort study among low-risk women receiving the policy of their preference in late-term pregnancy, a non-significant difference was found between induction of labour at 41 weeks and expectant management until 42 weeks in absolute risks of composite adverse (1.1 % versus 1.9 %) and severe adverse (0.3 % versus 1.0 %) perinatal outcome. The risks in this cohort study were lower than in the trial setting. There were no stillbirths among all 3642 women. Caesarean section rates were comparable.

Original languageEnglish
Article number100165
Number of pages9
JournalEuropean Journal of Obstetrics and Gynecology and Reproductive Biology: X
Early online date13 Oct 2022
Publication statusPublished - Dec 2022

Bibliographical note

Funding Information:
BWM reports consultancy for ObsEva. BMW has received research funding from Ferring and Merck.
The original RCT was funded by ZonMw: number NTR3431 , Netherlands Trial Registy .
BWM is supported by a NHMRC Investigator grant (GNT1176437).

We would like to thank all women who participated in this cohort, and all midwives, gynecologists residents and nurses of the participating centers. We would especially thank Loulou Schottelndreier (LS) and Julie van der Post for their contribution of the data management and Anita Ravelli for her comprehensive analysis of data from the Perinatal Registry of The Netherlands (Perined).


  • Cesarean section
  • Expectant management
  • Induction of labor
  • Late-term pregnancy
  • Maternal outcome
  • Perinatal outcome


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