Plain English Summary
Background and study aims
The length of a women’s cervix (cervical length) during pregnancy can affect the chances of premature labour. If a expectant mother has a short cervix, they can be at risk of going into premature labour and, therefore, premature birth of their baby. During pregnancy, the cervix (which is usually closed and rigid) with soften up over time, become shorter and open up as the baby grows and the body prepares to give birth. If the cervix begins to open too soon, premature birth may result. This study is looking at pregnant women with no symptoms pregnant with one baby, measuring the length of their cervix using vaginal ultrasound twice: at 18-20 weeks and at 21-23 weeks. The aims are to get an estimate of how many women have a short cervix during pregnancy, when it is best to measure the cervix to determine whether it is short, at what time is shortening of the cervix more likely to cause premature birth and how good the methods used to determine a short cervix are.
Who can participate?
Healthy pregnant women at between 18-20 weeks with one baby.
What does the study involve?
Participants have ultrasound examinations of their cervix at 18-20 weeks into their pregnancy and again at 21-23 weeks. At each session, the measurements are taken three times. The examination is carried out by a specially trained midwife. The women are not told the results of the measurements. Data is then collected to determine whether the method can successfully predict premature birth.
What are the possible benefits and risks of participating?
Not provided at time of registration
Where is the study run from?
Five hospitals in Sweden.
When is the study starting and how long is it expected to run for?
January 2014 to May 2017
Who is funding the study?
1. Swedish Research Council
2. Regional R & D Council, Uppsala / Örebro
3. Center for Clinical Research Dalarna
4. Southern Älvsborg Hospital
5. Regional R & D funds Västra Götaland
6. Hjalmar Svensson Research Fund
7. Löf (County Councils' Mutual Insurance)
Who is the main contact?
Dr Ulla-Britt Wennerholm
ulla-britt.wennerholm@vgregion.se
Trial website
Contact information
Type
Scientific
Primary contact
Dr Ulla-Britt Wennerholm
ORCID ID
http://orcid.org/0000-0003-2475-2226
Contact details
Sahlgrenska Universitetssjukhuset
Östra
Göteborg
41685
Sweden
+46313435580
ulla-britt.wennerholm@vgregion.se
Additional identifiers
EudraCT number
ClinicalTrials.gov number
Protocol/serial number
2014-10104-117089-114 The Swedish Research Council
Study information
Scientific title
Measurement of cervical length with vaginal ultrasound in the second trimester in asymptomatic women with a singleton pregnancy to predict preterm delivery: a Swedish multi-center observational study
Acronym
Study hypothesis
The general aim is to collect information to estimate if screening for preterm birth (PTB) with cervical length measurements at mid‐gestation using ultrasound and prophylactic progesterone treatment if the cervix is short is potentially cost‐effective in Sweden. The specific aims are to ‐ in a Swedish population:
1. Estimate the prevalence of ”short” cervix as measured by vaginal ultrasound at mid‐gestation in asymptomatic women with a singleton pregnancy
2. Find the optimal cervical length cutoff to predict PTB in asymptomatic women with a singleton pregnancy
3. Estimate the sensitivity and specificity with regard to PTB of ”short” cervix as measured by vaginal ultrasound (using different measurement techniques and definitions) at midgestation in asymptomatic women with a singleton pregnancy
4. Define the optimal gestational weeks (in the window from 18 to 23 gestational weeks) to measure cervical length to predict PTB in asymptomatic women with a singleton pregnancy
5. Investigate if a shortening of the cervix between gestational week 18‐20 and 21‐23 is more predictive of PTB than a single measurement of cervical length in asymptomatic women with a singleton pregnancy
6. Based on the results of 1., 2., 3., 4. and 5. and knowledge of the prevalence of PTB in singleton pregnancies in Sweden calculate the sample size of a Swedish randomized controlled trial to investigate the effect on PTB and neonatal outcome of screening asymptomatic women with a singleton pregnancy with ultrasound measurement of cervical length followed by progesterone treatment if the cervix is “short”
Ethics approval
Ethical committee at University of Gothenburg, Sweden, 13/11/2013 (ref: 825-13), 17/01/2014 (ref: T053-14), 08/12/2015 (ref: T972-15) and 25/02/2016 (ref: T122-16)
Study design
Multicentre prospective observational study
Primary study design
Observational
Secondary study design
Cohort study
Trial setting
Hospitals
Trial type
Screening
Patient information sheet
Condition
Pregnancy
Intervention
This is a Swedish multicentre prospective observational study. where healthy asymptomatic women with a singleton pregnancy will be examined with transvaginal ultrasound and measurement of cervical length during midtgestation.
Ultrasound examinations of the cervix are carried out by specially trained midwives, who have undergone standardized theoretical education and practical training. A certification system specially designed for this project is in place. The ultrasound examinations are performed vaginally with the woman in the lithotomy position with an empty urinary bladder. The vaginal ultrasound probe is slowly introduced into the vagina until the cervix becomes visible. Care is taken not to exert undue pressure on the cervix: the anterior and posterior lips of the cervix should appear equally thick. Ideally, the cervical canal should be horizontal in the image. The length of the closed cervical canal ( the line made by the interface of the mucosal surfaces) is measured as a straight line between the internal and external cervical os. If the isthmus is present its length is measured separately. Each measurement is taken three times, and all three are recorded. Images are stored for quality assessment.
These measurements are taken at 18+0-20+6 gestational weeks and 21+0-23+6 gestational weeks.
The women themselves and all medical staff are blinded to the results of the cervical length measurements. However, an ultrasound finding of bulging amniotic membranes is disclosed.
Intervention type
Procedure/Surgery
Phase
Drug names
Primary outcome measure
Ability of sonographic cervical length to predict preterm birth < 33 weeks, expressed as the area under the receiver operating characteristic curve (ROC) sensitivity, specificity, positive and negative likelhood ratio.
Secondary outcome measures
Ability of sonographic cervical length to predict spontaneous PTB <33 + 0 gestational weeks and for total and spontaneous PTB <28 + 0, <29 + 0, <30 + 0, <31 + 0, <32 + 0, <34 + 0 and< 35 + 0 gestational weeks.
All calculations will be made for:
1. the length of the closed cervical canal
2. if the isthmus is present its length is measured separately
3. from the external cervical os to the apparent (virtual) inner cervical os (if isthmus is present)
4. the length of the closed cervical canal + the isthmus.
Each measurement is taken three times and all three are recorded. Calculations will be made for the minimum, maximum and mean value and separately for measurements taken at 18 + 0 - 20 + 6 gestational weeks and 21+ 0 - 23 + 6 gestational weeks. using the ROC curves, the optimal method for measuring cervical length (which week, which measurement) and the optimal cervical length cutoff of the optimal method to predict PTB will be identified. The ability of a change in cervical length between the first (at 18 + 0 - 20 + 6) and the second (at 21 + 0 - 23 + 6) cervical length measurement to predict PTB. The prevalence of "short cervix" (using different definitions) will be calculated.
Overall trial start date
01/01/2014
Overall trial end date
01/11/2017
Reason abandoned (if study stopped)
Eligibility
Participant inclusion criteria
1. Asymptomatic women > 18 years old
2. With a live healthy singleton pregnancy in gestational week 18+0-20+6
3. Able to understand oral and written information
Participant type
Patient
Age group
Adult
Gender
Female
Target number of participants
11000
Total final enrolment
11486
Participant exclusion criteria
1. Fetal malformation
2. Rupture of membranes
3. Current vaginal bleeding
4. Ongoing miscarriage
5. Cerclage in situ
6. Current progesterone treatment at the time of recruitment
Recruitment start date
01/05/2014
Recruitment end date
30/06/2017
Locations
Countries of recruitment
Sweden
Trial participating centre
Sahlgrenska University Hospital
Gothenburg
41685
Sweden
Trial participating centre
Skåne University Hospital
Malmö/Lund
20502
Sweden
Trial participating centre
Karolinska University Hospital Solna/Huddinge
Stockholm
17176
Sweden
Trial participating centre
Falun's Hospital
Falun
79182
Sweden
Trial participating centre
Örebro University Hospital
Örebro
70185
Sweden
Sponsor information
Organisation
Region Västra Götaland
Sponsor details
Regionens Hus
Vänersborg
46280
Sweden
+46104410000
regionenshus@vgregion.se
Sponsor type
Hospital/treatment centre
Website
Funders
Funder type
Research council
Funder name
Swedish Research Council, Vetenskapsrådet
Alternative name(s)
Funding Body Type
Funding Body Subtype
Location
Funder name
Regional R & D Council, Uppsala / Örebro (Regionala FOU rådet Uppsala/Örebro)
Alternative name(s)
Funding Body Type
Funding Body Subtype
Location
Funder name
Centrum fÖr Klinisk Forskning Dalarna
Alternative name(s)
CKF
Funding Body Type
government organisation
Funding Body Subtype
government non-federal
Location
Sweden
Funder name
Southern Älvsborg Hospital (SÄS, Forskningsenhet)
Alternative name(s)
Funding Body Type
Funding Body Subtype
Location
Funder name
Regional R & D funds Västra Götaland (VGR Regionala FOU medel)
Alternative name(s)
Funding Body Type
Funding Body Subtype
Location
Funder name
Hjalmar Svensson Research Fund (Handlanden Hjalmar Svensson, Göteborg)
Alternative name(s)
Funding Body Type
Funding Body Subtype
Location
Funder name
Löf (County Councils' Mutual Insurance)
Alternative name(s)
Funding Body Type
Funding Body Subtype
Location
Results and Publications
Publication and dissemination plan
The results of the trial is expected to be presented during 2018 in scientific papers and at conferences.
IPD sharing statement: the data sharing plans for the current study are unknown and will be made available at a later date .
Intention to publish date
01/11/2018
Participant level data
To be made available at a later date
Basic results (scientific)
Publication list