Induction of labour versus expectant management for nulliparous women over 35 years of age: a multi-centre prospective, randomised controlled trial

Walker, Kate F. and Bugg, George and Macpherson, Marion and McCormick, Carol and Wildsmith, Chris and Smith, Gordon and Thornton, Jim (2012) Induction of labour versus expectant management for nulliparous women over 35 years of age: a multi-centre prospective, randomised controlled trial. BMC Pregnancy and Childbirth, 12 (Decemb). 8/1-8/8. ISSN 1471-2393

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Background: British women are increasingly delaying childbirth. The proportion giving birth over the age of 35 rose from 12% in 1996 to 20% in 2006. Women over this age are at a higher risk of perinatal death, and antepartum stillbirth accounts for 61% of all such deaths. Women over 40 years old have a similar stillbirth risk at 39 weeks as women who are between 25 and 29 years old have at 41 weeks.

Many obstetricians respond to this by suggesting labour induction at term to forestall some of the risk. In a national survey of obstetricians 37% already induce women aged 40–44 years. A substantial minority of parents support such a policy, but others do not on the grounds that it might increase the risk of Caesarean section. However trials of induction in other high-risk scenarios have not shown any increase in Caesarean sections, rather the reverse. If induction for women over 35 did not increase Caesareans, or even reduced them, it would plausibly improve perinatal outcome and be an acceptable intervention. We therefore plan to perform a trial to test the effect of such an induction policy on Caesarean section rates.

This trial is funded by the NHS Research for Patient Benefit (RfPB) Programme.

Design: The 35/39 trial is a multi-centre, prospective, randomised controlled trial. It is being run in twenty UK centres and we aim to recruit 630 nulliparous women (315 per group) aged over 35 years of age, over two years. Women will be randomly allocated to one of two groups:

Induction of labour between 390/7 and 396/7 weeks gestation.

Expectant management i.e. awaiting spontaneous onset of labour unless a situation develops necessitating either induction of labour or Caesarean Section.

The primary purpose of this trial is to establish what effect a policy of induction of labour at 39 weeks for nulliparous women of advanced maternal age has on the rate of Caesarean section deliveries. The secondary aim is to act as a pilot study for a trial to answer the question, does induction of labour in this group of women improve perinatal outcomes? Randomisation will occur at 360/7 – 396/7 weeks gestation via a computerised randomisation programme at the Clinical Trials Unit, University of Nottingham. There will be no blinding to treatment allocation.

Discussion: The 35/39 trial is powered to detect an effect of induction of labour on the risk of caesarean section, it is underpowered to determine whether it improves perinatal outcome. The current study will also act as a pilot for a larger study to address this question.

Item Type: Article
Keywords: Induction of labour, Advanced maternal age, Perinatal outcome, Caesarean delivery
Schools/Departments: University of Nottingham UK Campus > Faculty of Medicine and Health Sciences > School of Medicine > Division of Child Health, Obstetrics and Gynaecology
Identification Number:
Depositing User: Liu, Mr Zhenxing
Date Deposited: 09 May 2014 10:26
Last Modified: 13 Sep 2016 23:25

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