High Volume Foleys Increasing Vaginal Birth (High FIVe Birth) Pilot Trial
Phase: NA
Conditions: Labour; Induced, Pilot Study, Cervical Ripening
Sponsor: Sunnybrook Health Sciences Centre

High Volume Foleys Increasing Vaginal Birth (High FIVe Birth) Pilot Trial 
REB protocol  
March 22 2017 
 
PLAIN LANGUAGE ABSTRACT 
 
The rising rate of caesarean birth is of concern to both women and Obstetricians.  One 
quarter of Ontario women in their first pregnancy undergo an induction of labour, and 
one third of these women deliver by cesarean1. Prior to inducing labour, a woman's 
cervix often requires “ripening”, a process that makes it open and soft thus facilitating 
the induction  Most Canadian obstetricians use prostaglandins (a chemical messenger) 
for cervical ripening, and a minority use Foley catheters filled to a moderate volume2 
(30-60 cc), both of which are equivocal in risk of cesarean delivery. However, a recent 
meta-analysis from our group suggests  that Foley catheters filled to a higher 
volume, 80cc, as compared to the usual 30cc may be associated with a decreased 
risk of cesarean deliveries3.  
If 80cc Foleys are found to have a lower risk of cesarean, this would have a 
substantial positive impact on maternity care in Ontario, Canada and beyond. To 
assess this, a multi-centered randomized controlled trial comparing 80cc Foleys 
to prostaglandins is needed. Prostaglandins have been chosen as the comparison 
group as they are the most widely used method of cervical ripening in Canada, and 
therefore the most clinically relevant comparison group. To ensure the success of such 
a trial, a pilot trial must first be done. The proposed study is a pilot randomized 
controlled trial aimed at determining if recruitment into the large scale trial is 
possible, and optimizing its design. The discovery of a simple way to decrease 
the risk of cesarean would cause a paradigm shift in our approach to induction of 
labour. 
 
What is the main question or hypothesis for this proposal?  
Foley catheters are a non-pharmacologic method of cervical ripening without the side 
effects of prostaglandins for a fraction of the cost. The innovation is filling a Foley used 
for cervical ripening to a higher volume (80cc) then the volume currently being used (30-
60cc). Foleys filled to 80cc have been found on meta-analysis to trend towards a 
decreased risk of cesarean.  
  
The main question: Is it feasible (defined as a recruitment rate of 20% of eligible 
women) to run a large scale randomized controlled trial comparing 80cc Foleys to 
prostaglandins for cervical ripening to decrease cesarean delivery? 
 
Hypothesis: The hypothesis of the large scale trial is that High volume Foleys will 
decrease the risk of cesarean delivery compared to prostaglandins. The hypothesis of 
the current pilot study is that a randomized controlled trial is possible, in that we 
can enroll 20% of eligible women. 
 
 
 

High Volume Foleys Increasing Vaginal Birth (High FIVe Birth) Pilot Trial 
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PROJECT NARRATIVE PROPOSAL 
Background: 
Approximately 1/3 of first-time mothers (nulliparous women) undergoing induction of 
labour deliver by cesarean 1. Cesarean delivery can have negative consequences to the 
initial
4,5,6 and subsequent
7 pregnancies. Women who have a cesarean in their first 
pregnancy are more likely to have a cesarean in their following pregnancies
1 and this 
group is the largest contributor to the overall cesarean delivery rate
1. Therefore, 
targeting interventions that prevent cesareans in nulliparous women undergoing 
induction of labour will have a substantial impact on the overall cesarean delivery rate.  
 
Adequate ripening or preparing the cervix before induction has been found to decrease 
the risk of cesarean8-11. This can be done by a variety of methods, such as 
prostaglandins (a chemical messenger) or a Foley filled to a moderate volume of fluid. 
These methods have been found to be equal regarding the risk of cesarean delivery12. 
However, a meta-analysis by our team discovered a trend towards a decreased 
risk of cesarean when cervical ripening is undertaken with Foleys filled to a high 
volume of fluid (80cc) compared to those filled to a low volume (30cc)3. 
 
 
Most Canadian Obstetricians use prostaglandins for cervical ripening2. To assess if 
80cc Foleys result in a lower risk of cesarean, they need to be compared to the 
Canadian standard of prostaglandins. Therefore a randomized controlled trial is 
required.  
 
The Greater-Toronto-Area Obstetric (GTA-OB) Network is a group of hospitals 
committed to facilitating research and will be the setting for the planned large scale trial. 
The large scale trial will aim to demonstrate a difference in the rate of cesarean from 
38% to 31%, which will require the enrolment of 1442 women. It has been estimated 
that there are 5,437 women who will meet entry criteria in the GTA-OB network each 
year, if ½ are approached, 20% will need to consent to complete the trial in 3 years. 
Therefore, this pilot study will determine if this recruitment rate is potentially 
achievable and will inform design strategies to ensure its success. 
 
The discovery of a simple, non- pharmacological, cost effective manner of cervical 
ripening that decreases the risk of cesarean would change clinical practice and 
significantly improve safety for the 33,000 Canadian women and their babies who 
undergo cervical ripening each year.13 This pilot trial is a crucial step towards this 
discovery. 
 
 
 

High Volume Foleys Increasing Vaginal Birth (High FIVe Birth) Pilot Trial 
REB protocol  
March 22 2017 
 
Objectives: 
The primary objective for this pilot trial is to determine the probability that an eligible 
woman will agree to be randomized into the trial comparing 80cc Foleys to 
prostaglandins for cervical ripening. This study aims to assess if it is possible to obtain a 
recruitment rate of 20%.  
 
The secondary objective will be a systematic evaluation of the pilot trial process to guide 
full-scale study design. 
 
Rationale:  
 
Why is this study needed now? 
Successful vaginal birth is the safest mode of delivery for both women and babies, 
whereas a cesarean delivery is associated with a higher rate of neonatal and maternal 
morbidity4-7. The vast majority of pregnant women would prefer to have a vaginal birth14. 
The goal of induction of labour is vaginal birth and needing a cesarean section is the 
top fear of women undergoing induction of labour15. Women with a failed induction 
have a feeling of wasted effort and pain, feel let down and disappointed16 .The 
healthcare system will also benefit, as first time cesarean deliveries are the 
leading cause of repeat cesarean deliveries1. Foleys are approximately 70 times 
less expensive than prostaglandins17. This project will provide the pilot study needed 
to discover if a Foley filled to 80cc reduces the risk of Cesarean delivery compared to 
prostaglandins, and will provide essential information needed for the successful 
execution of the large multicenter RCT. The discovery of an inexpensive method of 
cervical ripening that decreases the risk of cesarean delivery would have a vast impact 
maternal and neonatal morbidity, patient satisfaction and health care costs. 
 
What is the clinical significance?: 
The WHO recommends a cesarean section rate of 10-15% 18, and the Canadian rate of 
28% is significantly above this19. Induction of labour in first time mothers results in a 
cesarean section 1/3 of the time1, and therefore it is essential that the process of 
induction is undertaken in such a way that it decreases this risk. Low volume Foleys 
have already proven to be a safe and cost effective method of cervical ripening12, 
however, prostaglandins are used preferentially by Canadian obstetricians because of 
ease of use (require less set up) and perceived patient preference.2. However, if filling 
the Foley to 80cc was found to decrease the risk of cesarean delivery, 
overcoming the environmental barriers to Foley use would be justified. By simply 
filling the same Foley to a higher volume, meta-analysis data suggests it is possible to 
decrease the risk of cesarean3. This pilot study has the potential to lead the way 
towards a non-medication based intervention that has the potential to decrease 
the risk of cesarean and support vaginal birth in Canada and beyond. 
 
How will the results of this trial be used? 
Rising Caesarean rates are concerning. Low volume Foleys (30-50cc) have been 
compared to prostaglandins in clinical trials20 and meta-analysis21 with no difference in 
cesarean rate, however Foleys filled to high volumes were not included in these studies 

High Volume Foleys Increasing Vaginal Birth (High FIVe Birth) Pilot Trial 
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March 22 2017 
 
and may decrease the risk of cesarean. The GTA-OB network has the capacity to 
support this needed clinical trial, however this will not be possible without 
ensuring that adequate recruitment will take place. This pilot will assess if 
adequate recruitment is achievable, and provide a platform for a rolling 
evaluation of recruitment strategies to improve the chance of large scale trial 
success.   
 
Foundational work by the team: 
A meta-analysis by the team compared high volume Foleys to low volume Foleys and a 
trend towards a decreased rate of cesarean with high volume Foleys was 
demonstrated3.  This was the foundational discovery suggesting a method to 
decrease the risk of cesarean delivery.  
 
A national survey of obstetricians showed a high degree of interest in trial participation. 
It also found the majority of obstetricians (85%) prefer prostaglandins because of ease 
of use, and a perception of patient preference,2 (although this is not supported in the 
literature).22,23 This survey demonstrated sufficient interest in a trial, and that the 
important question to ask that would result in clinical practice change is “Do Foleys filled 
to 80ccs result in a lower risk of cesarean than prostaglandins?” 
Most obstetricians have used Foleys in the last year2, demonstrating that the skills 
needed to make use of Foleys filled to 80cc are already in place. To facilitate the 
translation of Foley placement skills to our future obstetricians, we have also developed 
a Cervical Ripening Training Model24.  
 
Other studies have made use of Foleys filled to high volumes without evidence of 
adverse effects 25-27, and Foleys have generally found to have a higher safety profile 
than prostaglandins, including decreased overall pain, decreased strong contractions 
causing changes in the fetal heart rate, and decreased postpartum hemorrhage8,20. Our 
team has also done materials testing and found a standard 30cc Foley has a rupture 
volume of 160cc +/- 11.8cc28. 
 
A trial is needed to assess if Foleys filled to 80ccs can decrease the risk of cesarean. 
However, prior to this, a pilot is required to demonstrate the feasibility of successful 
recruitment, and to understand unforseen challenges and rate limiting steps that 
may prevent the successful completion of the trial. 
 
Description of the team 
Anne Berndl: PI, Maternal Fetal Medicine specialist, clinician investigator at 
Sunnybrook Health Science Centre, MSc in Health Research Methodology. Assistant 
Professor, University of Toronto, Associate Scientist at the Sunnybrook Research 
Institute. She will oversee all aspects of the project (40% protected time).  
Jon Barrett: Chief of Maternal-Fetal Medicine at Sunnybrook Health Sciences Centre, 
Director of Women and Babies Research Program at Sunnybrook Research Institute. 

High Volume Foleys Increasing Vaginal Birth (High FIVe Birth) Pilot Trial 
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Chair of the GTA-OBS network, Professor in the department of obstetrics and 
gynecology at the University of Toronto. He has contributed to the design of the trial, 
and will provide leadership and support though Sunnybrook and the GTA-OB network 
(1/2 day/week) 
Elizabeth Asztalos: Neonatologist at Sunnybrook Health Sciences Center, Neonatal 
Research Director for the Department of Newborn and Developmental Pediatrics at 
Sunnybrook. Associate Professor in the departments of Pediatrics and Obstetrics and 
Gynecology at University of Toronto. She has contributed to the design and  will 
contribute to the analysis. (1hr/ week) 
Sarah McDonald: Tier II Canada Research Chair, Associate Professor in the 
Department of Obstetrics and Gynecology at McMaster University, Associate Member 
of the Department of Clinical Epidemiology and Biostatistics. She has contributed to the 
design and  will contribute to the analysis. Interpretation of the data, and knowledge 
translation (1 hr/ week).  
Kellie Murphy: Maternal-Fetal Medicine specialist at Mount Sinai Hospital, Associate 
Professor in the Department of Obstetrics and Gynecology and Institute of Health 
Policy, Management and Evaluation at University of Toronto. She has contributed to the 
design and  will contribute to the analysis, interpretation of the data, and knowledge 
translation (and organize recruitment through Mount Sinai. (1hr/ week) 
 
Alex Kiss: Scientist and statistician at the Sunnybrook Research Institute, Assistant 
Professor in the department of health policy, management and evaluation at the 
University of Toronto. He will contribute to the analysis. 
Approach and Work Plan  
Study Design: The proposed study is a multicentre open label randomized controlled 
trial pilot. It will include nulliparous (women who have never given birth) women with 
term pregnancies requiring cervical ripening prior to induction of labour and takes place 
at Sunnybrook and NorthYork General Hospitals . The intervention involves 
randomizing women to cervical ripening with either a Foley filled to 80cc, or 
prostaglandins. We will register the trial at Clinicaltrials.gov 
Primary research question: What is the probability that eligible women will agree to be 
randomized into the trial evaluating high volume Foleys to prostaglandins for cervical 
ripening. 
Primary outcome: The percentage of eligible women who are approached to participate 
in the study that are enrolled and randomized to either the use of a high volume Foley 
or prostaglandin for cervical ripening. 

High Volume Foleys Increasing Vaginal Birth (High FIVe Birth) Pilot Trial 
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March 22 2017 
 
Other outcomes: A rolling assessment of the study process to evaluate issues that 
may affect enrolment rates. These will be evaluated under the categories of technical, 
environmental, staff personnel, patient, and data collection issues. Other important 
processes outcomes include protocol compliance, ease of intervention, physician and 
patient satisfaction. 
Inclusion criteria 
● Nulliparous women 37 weeks and 0 days to 41 weeks and 6 days gestational 
age (term) requiring cervical ripening  
● Health care provider feels it is possible to administer either method of cervical 
ripening. 
● Bishop score of 6 or less 
● Live, singleton, cephalic fetus 
 
Exclusion Criteria 
● Non-viable fetus  
● Contraindication to cervical ripening, labour induction or labour 
● Prior attempt at induction of labour in this pregnancy 
● Spontaneous rupture of fetal membranes  
● Evidence of labour or regular uterine contractions  
● Lack of consent  
● No one available to perform randomisation 
 
How will participants be identified and followed? 
An educational session for nurses, midwives, residents and physicians will be done at 
each centre. A detailed study information package will be available to give to women 
who meet entry criteria. Patients may choose to sign a consent form for the study in the 
antenatal period, or on presentation for cervical ripening. 
Patients presenting for cervical ripening and meeting entry criteria will be invited to 
participate in the study and informed consent will be obtained by the research assistant. 
The research assistant will access the online randomization service at the Sunnybrook 
clinical trials unit, and the patient will be randomized to either prostaglandin or Foley 
filled to 80cc. At this time, all care and decision-making will be provided as per the 
woman’s care provider. All approached women, whether they consent to be part of the 
study or not, will be invited to complete a short questionnaire regarding knowledge of 
the study prior to the day of induction and feelings towards research. 
 
RAs will record in Redcap the date and time of delivery for enrolled women, as well as 
mode of delivery (vaginal or cesarean section) and any serious adverse events 
(maternal death or ICU admission, neonatal death or unplanned ICU admission) 
 
 

High Volume Foleys Increasing Vaginal Birth (High FIVe Birth) Pilot Trial 
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Data Collection 
Data collection for patient information will be collected electronically through RedCap. 
Semi-structured interviews from physicians, nurses, and residents will be conducted by 
the PI or delegate and recorded on paper or via email. 
Patient knowledge and satisfaction surveys will be provided by the research assistant 
and completed by the patients when approached about participating in the study. 
  
How will outcome measures be captured? 
The primary outcome measure of percent of women recruited will be captured by the 
number of women who undergo the randomized intervention divided by the number of 
women who are eligible. These numbers will be kept by the research assistants 
enrolling participants in the trial. Demographic data for recruited women will be captured 
by the research assistants from patient charts. 
For process outcomes, semi-structured interviews will be conducted with staff, chief 
residents and charge nurses and will be recorded in writing. Patients will be asked to fill 
a short patient satisfaction survey. These process outcomes will be captured every 3 
months. 
 
Analysis: 
The primary outcome is a descriptive statistic of number of women enrolled/ number of 
eligible women. Process outcomes that are quantitative in nature will be described using 
descriptive statistics. Qualitative process outcomes will be evaluated via group 
discussion and consensus at each steering committee meeting. 
 
Sample Size calculation 
The primary outcome is the proportion of eligible women who consent and are 
randomized into the pilot trial. It is estimated that 10-15 women will be approached per 
week over a 15 month time frame. This is based on a total population of 4000 deliveries 
per year at Sunnybrook and 6000 at North York General Hosptial. . One half are 
nulliparous, and 90% are term. 25 % of these women will undergo induction of labour, 
meaning approximately 24 women per week. Not all inductions will take place during 
day time hours or during weekdays at Sunnybrook, however almost all inductions at 
North York General are pre-scheduled to take place in the afternoon during the 
workday,  resulting in an approximation of 10-15 women approached per week or 630-
975 women approached over a 15 month time frame. Our target proportion is 20%. For 
an expected consent rate of 20%, the sample of 130-195 will provide the 95% 
confidence interval around this estimate to have bounds ranging from 16.9% to 23.3%, 
and from 17.5% to 22.7% respectively 
 
 
 

High Volume Foleys Increasing Vaginal Birth (High FIVe Birth) Pilot Trial 
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Timeline  
 
The start-up time includes hiring of RAs, ethics, contracts and data sharing agreements, 
information sessions and distribution of study information materials. 
Recruitment and data collection will take place in 3 month blocks. The recruitment rate 
and feedback from clinicians will be assessed at a steering committee meeting every 3 
months, after which strategy changes will be implemented. 
The final analysis will take place in the final 3 months of the study. 
 
 
 

High Volume Foleys Increasing Vaginal Birth (High FIVe Birth) Pilot Trial 
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Project Outcome Evaluation Metrics  
Anticipated outcomes: 
The primary outcome will be the percent of eligible participants approached for the trial 
that are enrolled in the trial and undergo randomization. A recruitment rate of at least 
20% will be considered a success. 
 
Outcome 
Method of capture 
Recruitment rate 
Number of women enrolled/ number of 
eligible women as found by assessing 
demographics of women scheduled for 
induction as per birth unit records  
Pt demographics of those enrolled and not 
enrolled (age, indication for induction, 
gestational age) 
Patient chart 
Recruitment trends/ days/ time of 
increases recruitment 
RA recruitment data 
Staff Physician, resident and charge nurse 
at times of enrollment 
Hospital records, RA will assess when in 
triage 
Rate of protocol compliance 
Assessment of appropriate inclusion/ 
exclusion criteria from chart, feedback 
from RAs 
Physician/ resident/ nursing satisfaction 
and attitudes towards recruitment 
Semi-structured interviews q3 months 
Patient satisfaction/ attitudes towards 
recruitment 
Patient surveys 
Environmental, technical, patient, staff 
issues, data collection issues that facilitate 
recruitment or deter from recruitment 
Semi structured interviews q3 months 
 
The study process will be evaluated every three months. The Steering committee will 
review the recruitment data, interviews and patient surveys, resulting in changes in the 
execution of the pilot for the next 3 months, with the goal of a) improving recruitment 
rate through strategy development and b) discovering unforeseen challenges to the 
success of the study. This information will ultimately be incorporated into the large scale 
study protocol. 
 
 

High Volume Foleys Increasing Vaginal Birth (High FIVe Birth) Pilot Trial 
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Ethics: 
Trained research assistants will obtain informed consent in writing from all patients. 
Staff, residents and nurses who provide feedback verbally will sign a consent form. 
Those who choose to respond by email will be assumed to be consenting by the 
submission of the email. All responses will be coded to a study code to maintain the 
confidentiality of those who participate. The master key linking these codes will be 
destroyed after full analysis of the study. 
Canada’s rising cesarean delivery rate requires creative and innovative solutions. This 
pilot is an essential step towards discovering a safe, cost effective way to decrease the 
risk of cesarean delivery and improve safety and satisfaction for women and babies. 
 
References 
1.(5). Better Outcomes Registry & Network (BORN) Ontario. Perinatal Health Report 
2009–2010. Waterloo Wellington and Hamilton Niagara Haldimand Brant—LHINs 3 & 4. 
Ottawa ON: BORN; 2011. 
 
2.(12). Berndl A, Armson A, Murphy K, McDonald S Methods of Cervical Ripening Prior 
to Induction of Labour at Term: A survey of Canadian Practitioners J Obstet Gynaecol 
Can 2015; 37 (1):89 
 
3.(11). Berndl A, El-Chaar D, Murphy K, McDonald S. Does Cervical Ripening at Term 
Using a High Volume Foley Catheter Result in a Lower Caesarean Section Rate Than a 
Low Volume Foley Catheter? A Systematic Review and Meta-Analysis J Obstet 
Gynaecol Can 2014;36(8):678–687 
 
4.(1)Liu S, Liston RM, Joseph KS, Heaman M, Sauve R, Kramer MS, et al. Maternal 
mortality and severe morbidity associated with low-risk planned cesarean delivery 
versus planned vaginal delivery at term. CMAJ 2007;176(4):455–60. 
 
5.(2). Farchi S, Di Lallo D, Franco F, Polo A, Lucchini R, Calzolari F, et al. Neonatal 
respiratory morbidity and mode of delivery in a populationbasedstudy of low-risk 
pregnancies. Acta Obstet Gynecol Scand 2009;88(6):729–32. 
 
6.(3). Sheiner E, Levy A, Feinstein U. Risk factors and outcome of failure to progress 
during the first stage of labor: a population-based study. Acta Obstet Gynecol 2002: 
81:222–6. 
 
7.(4). Huang X, Lei J, Tan H, Walker M, Zhou J, Wen SW. Cesarean delivery for first 
pregnancy and neonatal morbidity and mortality in second pregnancy. Eur J Obstet 
Gynecol Reprod Biol 2011;158(2):204–8. 
 

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8.(6). Jozwiak M, Bloemenkamp KWM, Kelly AJ, Mol BWJ, Irion O, Boulvain M. 
Mechanical methods for induction of labour. Cochrane Database Syst Rev 
2012;3:CD003. 
 
9(7). Isono W, Nagamatsu T, Uemura Y, Fujii T, Hyodo H, Yamashita T, et al. Prediction 
model for the incidence of emergent cesarean section during induction of labor 
specialized in nulliparous low-risk women. J Obstet Gynaecol Res 2011;37(12):1784–91 
 
10.(8). Vrouenraets FP, Roumen FJ, Dehing CJ, van den Akker ES, Aarts MJ, Scheve 
EJ. Bishop score and risk of cesarean delivery after induction of labor in nulliparous 
women. Obstet Gynecol 2005;105(4):690–7. 
 
11.(9). Johnson D. Risk of cesarean delivery after induction at term in nulliparous 
women with an unfavorable cervix. Am J Obstet Gynecol 2003;188(6):1565–72. 
 
12.(10). Leduc D, Biringer A, Lee L, Dy J; SOGC Clinical Practice Obstetrics 
Committee. Induction of labour. SOGC Clinical Practice Guideline no. 296, September 
2013. J Obstet Gynaecol Can 2013;35(9):840–57. 
 
13.(27). (http://www.statcan.gc.ca/tables-tableaux/sum-som/l01/cst01/demo04a-
eng.htm based on 388,725 births x 92% term x ½ nulliparous X ¼ induced x 75% 
needing cervical ripening) 
 
14.(21). E. E. BUYUKBAYRAK, O. KAYMAZ, B. KARS, A. Y. K. KARSIDAG, E. 
BEKTAS, O. UNAL & C. TURAN. Caesarean delivery or vaginal birth: Preference of 
Turkish pregnant women and influencing factors  Journal of Obstetrics and 
Gynaecology, February 2010; 30(2): 155–158  
 
15.(22.)Women's concerns and satisfaction with induced labour at term in a Nigerian 
population.Nigerian Postgraduate Medical Journal. 20(1):1-4, 2013 Mar. Ezeanochie M; 
Olagbuji B; Ande A. 
 
16.(23).Henderson J, Redshaw M. Women's experience of induction of labor: a mixed 
methods study. Acta Obstet Gynecol Scand. 2013 Oct;92(10):1159-67. 
 
17.(29): direct communication with hospital pharmacy, Sunnybrook Health Sciences 
Centre, November 10th 2015 
 
18. WHO, HRP. WHO statement on caesarean section rates. April 2015, WHO 
reference number WHO/RHR/15.02 
 
19. Public Health Agency of Canada. Perinatal Health Indicators for Canada 2013: a 
Report of the Canadian Perinatal Surveillance System. Ottawa, 2013. 
 

High Volume Foleys Increasing Vaginal Birth (High FIVe Birth) Pilot Trial 
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20.(13). Jozwiak M, Oude Rengerink K, Benthem M, van Beek E, Dijksterhuis MG, de 
Graaf IM, et al. Foley catheter versus vaginal prostaglandin E2 gel for induction of 
labour at term (PROBAAT trial): an open-label, randomised controlled trial. Lancet 
2011;378:2095–103 
 
21.(14). Jozwiak M, Bloemenkamp KWM, Kelly AJ, Mol BWJ, Irion O, Boulvain M. 
Mechanical methods for induction of labour. Cochrane Database Syst Rev 
2012;3:CD003. 
 
22.(25). Pennell CE, Henderson JJ, O’Neill MJ, McCleery S, Doherty DA, Dickinson JE. 
Induction of labour in nulliparous women with an unfavourable cervix: a randomised 
controlled trial comparing double and single balloon catheters and PGE2 gel. BJOG 
2009;116:1443–52. 
 
23.(26). Henry A, Madan A, Reid R, Tracy SK, Austin K, Welsh A, et al. Outpatient 
Foley catheter versus inpatient prostaglandin E2 gel for induction of labour: a 
randomised trial. BMC Pregnancy Childbirth 2013;13:25 
 
24. Michael A, Barrett J, Cohen H, Hui D, Ladhani N, Melamed N, Nevo O, Berndl A. 
The development of a Foley Catheter Cervical Ripening Model for Residency Education 
and Training J Obstet Gynaecol Can 2015; 37(1):91 
 
25.(15). Levy R, Kanengiser B, Furman B, Arie AB, Brown D, Hagay ZJ. A randomized 
trial comparing a 30-mL and an 80-mL Foley catheter balloon for preinduction cervical 
ripening. Am J Obstet Gynecol 2004;191(5):1632–6. 
 
26.(16). Kashanian M, Nazemi M, Malakzadegan A. Comparison of 30-mL and 80-mL 
Foley catheter balloons and oxytocin for preinduction cervical ripening. Int J Gynaecol 
Obstet 2009;105(2):174–5. 
 
27.(17). Delaney S, Shaffer BL, Cheng YW, Vargas J, Sparks TN, Paul K, et al. Labor 
induction with a Foley balloon inflated to 30 mL compared with 60 mL: a randomized 
controlled trial. Obstet Gynecol 2010;115(6):1239–45. 
 
28. Pittini A, Barrett J, Cohen H, Hui D, Ladhani N, Melamed N, Nevo O, Berndl A.This 
Materials testing for the High FIVe Birth Trial (High Volume Foleys Increasing Vaginal 
Birth): Steps for Adaptation to Facilitate Trial Participation. J Obstet Gynaecol Can 
2015; 37(1):90