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  • 00:14

    KATE WALKER: My name's Dr. Kate Walker.I'm the clinical assistant professorin obstetrics and gynecology at the University of Nottingham.[Dr. Kate Walker, Clinical Assistant Professorof Obstetrics and Gynecology] And I split my time evenlybetween clinical work, looking after women in pregnancyand childbirth, and my research work focuses on perinatalrandomized controlled trials--so trials in pregnancy, childbirth,

  • 00:35

    KATE WALKER [continued]: and in the neonatal period.I'm going to talk about the 35/39 study.This was a multi-center randomized trialof induction of labor at 39 weeksversus expectant management for womenexpecting their first baby over the age of 35.And I did this study as part of my PhD, whichI finished in 2016.The study involved colleagues at Nottingham University

  • 00:57

    KATE WALKER [continued]: Hospital's NHS Trust, and colleaguesin obstetrics and gynecology at the University of Nottingham,Professor Gordon Smith at the University of Cambridge,and SANDS, who are the leading charity supportingwomen affected by stillbirth in the UK.[How did you formulate your research question?]

  • 01:21

    KATE WALKER [continued]: The first idea for the study came from a clinicianwho I worked with in Nottingham, who was offering inductionof labor to mums who were over the age of 35, particularlyif it was their first baby.And the rationale for offering induction of labor at 39 weeksis that women over 35 have a small age-related increased

  • 01:42

    KATE WALKER [continued]: risk of stillbirth, which is when the baby dies in the womb.And that clinician felt because of that small age-relatedincreased risk, we should offer an earlier induction of laborthan we would to, say, mothers whoare aged 25, when we normally offer induction about 41 weeks.And that was kind of the rationale for the trial.

  • 02:02

    KATE WALKER [continued]: The reason, at the time, people felt maybe induction of laborwasn't a good idea for these women was that we alsoknew that women over 35 particularlywith their first baby, had a muchhigher rate of obstetric interventionlike needing a cesarean section, needing an instrumental birth.And so the concern was that you would offer induction of labor

  • 02:22

    KATE WALKER [continued]: to prevent a very small increased risk of stillbirth,but increase adverse outcomes for the motherthrough offering induction.And that was the background to the study.[How did you decide on your participant inclusioncriteria?]So we thought very carefully about whoto involve in terms of our participants for the study.

  • 02:45

    KATE WALKER [continued]: A big discussion back in the day wasabout whether to include just women expectingtheir first baby, who have higher rates of stillbirth,but also higher rates of obstetric intervention,or to include all women over the age of 35expecting their first, second, third, fourth baby.We decided to restrict to women expecting their first baby just

  • 03:05

    KATE WALKER [continued]: because those women had both a small increased riskof stillbirth compared to women havingtheir second or third baby, but also theyhad higher rates of obstetric Intervention.[How did you design the trial?]We clearly decided who our participantsshould be-- women expecting their first baby

  • 03:27

    KATE WALKER [continued]: over the age of 35.We then decided on our intervention.It was clear that induction at 39 weeksrepresents the optimal timing for a baby.It's when the baby's lungs are fully developed,but it's also when the risk of stillbirthincreases quite dramatically.So 39 weeks seemed like the perfect intervention--

  • 03:47

    KATE WALKER [continued]: best benefit for baby.And our comparison group was expectant management.And that's basically awaiting a situation whereeither labor starts spontaneouslyor the mother needs to be induced or have a cesareanfor a medical indication.So it's basically a deliver or delay trial.That's what we tend to call them. [deliver or delay trial]In terms of our outcome, the study

  • 04:09

    KATE WALKER [continued]: was only powered to see whether induction of laborhad caused a change in the rates of cesarean sectionin the mother.So although we were doing it because we were worriedabout increased risk of stillbirth,the study was never powered to show a reduction in stillbirth.That would have involved a study of over 10,000 women.[How did you decide on this trial design?]

  • 04:35

    KATE WALKER [continued]: Just because you reduce bias by having a randomized trial,you make sure that women in both arms of the studyare equal in terms of their baseline characteristics.[How did you recruit participantsfor your research?]The trial was funded with UK public funding

  • 04:55

    KATE WALKER [continued]: through the RfPB.[Funder - NIHR Research for Patient Benefit (RfPB)] Andso recruitment was restricted to the UK.And we needed over 40 sites across the length and breadthof the UK.[What challenges did you face in recruitingparticipants?]What the actual biggest challengeof the study as a whole was that,

  • 05:16

    KATE WALKER [continued]: although clinicians were in equipoise aboutwhether induction of labor was preferable to expectantmanagement for women over 35, actually,women themselves didn't seem to be at equipoise.So women felt very strongly one way or the other.When we told them about the study,they were either very keen to be induced becauseof their age-related increased risk of stillbirth,

  • 05:38

    KATE WALKER [continued]: or very keen to avoid the downsides of induction--that it's longer, that it's more painful,time away from your family and home.So the biggest barrier to the trialwas that it was difficult to get women to agree to join.And we based our logistics for the studyon needing to approach women so that 30%--

  • 06:01

    KATE WALKER [continued]: expecting 30% to agree to join, but actually only about 10%of women agreed to join.So it meant we had to screen huge, huge numbers of women,over 6,000, to get 600 women to join the study.And for me, that was the biggest hurdle and the greatestlearning curve for the study.

  • 06:21

    KATE WALKER [continued]: [What ethical considerations were there for yourresearch?]I guess the biggest issue was, is it ethical to leave womenover the age of 35 to 41 weeks gestation,if we know they have an increased risk of stillbirth.I guess the counterargument is that those women currently

  • 06:42

    KATE WALKER [continued]: were not being offered induction,and we were hoping to get the evidenceto allow women to make an informed choice about inductionor not.So the ethical issue about not inducing women,it was sort of counterbalanced by the factthat we needed to get the evidence to see what's safe.[How did you collect the data?]

  • 07:07

    KATE WALKER [continued]: We were very fortunate that the studywas adopted on the NIHR clinical research networkportfolio, which means that we had research midwives fundedby that portfolio at every hospitalthat we selected to take part in the study.So those research midwives were the absolute backboneof the study.They recruit.They screened all the participants, recruited them,

  • 07:28

    KATE WALKER [continued]: and then completed individual data on the trial database,hosted by Nottingham Clinical Trials Unit.So we collected individual patient data for the study.[How did you analyze the data?]The data was analyzed with an intention to treat principle--

  • 07:50

    KATE WALKER [continued]: so women were analyzed according to the groupthat they were initially assigned,irrespective of whether they receivedthe intervention or not. [intention to treat analysis]And then our statisticians did the analysis of the study,adjusting for important confounders.[What were your findings and how did you disseminate them?]

  • 08:12

    KATE WALKER [continued]: This was actually the first randomized trialthat had ever been done in the world of deliver or delayfor women of advanced maternal age,or aged over 35 years of age.And the main outcome we were looking atwas cesarean section.And we found no significant differencein cesarean section rates in womenwho were induced versus women who were managed expectantly.

  • 08:34

    KATE WALKER [continued]: And the relative risk was as close to 1 as you could get,which was very surprising.We thought, perhaps, there might be a slight increasedrisk of cesarean in the mothers that we induced,given their background rates of cesareanare much higher, and surprising there was no difference.There was also no other differencein terms of any short-term motheror baby outcomes in the study.

  • 08:55

    KATE WALKER [continued]: And so this trial has led to a real sea change in practice,certainly in the UK where, certainly,in the hospital I work at, it's completely routinenow to offer mothers who are over 35 induction of laborto try and forestall some of that risk of stillbirth.And that's a result of the 35/39 trial.So we disseminated the results of our studythrough international conferences,

  • 09:15

    KATE WALKER [continued]: national conferences, and we alsoheld a trial results meeting, where all our partners came,and the results were disseminatedto all those research midwives who busilycollected all the data for us.And SANDS, our charity partner who work very closelyto support mothers who are affected by stillbirth,helped to disseminate a lay summary of the results.

  • 09:35

    KATE WALKER [continued]: We also wrote to every woman who took part in the studywith a lay summary of the results,and they were available on our trial website.[What practical lessons did you learn from this researchproject?]The single biggest lesson I have learned,and I've taken forward for the randomized trialsthat I work in now, is to do an internal pilot,

  • 09:57

    KATE WALKER [continued]: to make sure that you have a really clear idea of howacceptable the study is to women, in my case.[Are there any tools or resources you would recommend?]There's excellent resources on the NIHR websitewith principal investigator toolkits.

  • 10:18

    KATE WALKER [continued]: And certainly my institution, the University of Nottingham,has fabulous, local resources for anybodywho's at Nottingham.

Video Info

Publisher: SAGE Publications, Ltd.

Publication Year: 2021

Video Type:Case Study

Methods: Clinical trials, Clinical research, Data collection, Randomized controlled trials, Focus groups

Keywords: Caesarean section; childbirth; clinical research; clinical trials; data analysis; data collection; labor induction; midwives; participation (research); pregnancy; randomized controlled trials; recruitment; research design; research ethics; Stillbirth ... Show More

Segment Info

Segment Num.: 1

Persons Discussed:

Events Discussed:



Dr. Kate Walker, Clinical Assistant Professor in Obstetrics and Gynecology at the University of Nottingham, discusses investigating labor induction using a randomized controlled trial, including participant selection and recruitment, trial design, and other considerations.

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Investigating Labor Induction Using a Randomized Controlled Trial

Dr. Kate Walker, Clinical Assistant Professor in Obstetrics and Gynecology at the University of Nottingham, discusses investigating labor induction using a randomized controlled trial, including participant selection and recruitment, trial design, and other considerations.

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