Condition category
Pregnancy and Childbirth
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Not provided at time of registration

Trial website

Contact information



Primary contact

Prof G.H.A. Visser


Contact details

University Medical Centre Utrecht
Department of Obstetrics
P.O. Box 85500
3508 GA
+31 (0)30 250 6426

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title


STAN versus CTG + FBS

Study hypothesis

Cardiotocography (CTG) is worldwide the method for foetal surveillance during labour. However, CTG alone shows many false positive results and without foetal blood sampling (FBS) it results in an increase in operative deliveries without an improvement of foetal outcome. FBS requires additional expertise, is invasive and has often to be repeated during labour. Two randomised controlled trials have shown that a combination of CTG and non-invasive ST-analysis (of the foetal electrocardiogram [ECG]) reduces the rates of metabolic acidosis and instrumental delivery. However, in both randomised controlled trials FBS was still performed in both arms, and it is therefore still unknown if the observed results were indeed due to the ST-analysis or to the use of FBS in combination with ST-analysis.

Intrapartum foetal monitoring with the STAN-method (cardiotocograpy with ST-analysis of the foetal ECG) results in less neonates with metabolic acidosis and less interventions for foetal distress as compared to monitoring with cardiotocography in combination with foetal blood sampling.

As of 16/07/2007 the power calculation was changed, and the target number of participants was increased from 2400 to 5100; see interventions section for more details.

Ethics approval

Medical Ethics Committee University Medical Centre Utrecht, 17/11/2005, ref: 05/157-K

Study design

Randomised active controlled parallel-group multicentre trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet


Women in labour with a high-risk pregnancy


Women will be randomly assigned to routine care including foetal monitoring by cardiotocography with foetal blood sampling (CTG + FBS group) or to the index group including cardiotocography with ST-analysis (CTG + ST group). Clinical management in the CTG + FBS group (routine care) will be guided by guidelines produced by the International Federation of Gynaecology and Obstetrics (FIGO). FBS is recommended in case of a suboptimal or abnormal CTG pattern. In cases with scalp blood pH lower than 7.20 or preterminal cardiotocograms delivery is recommended. In the CTG + ST group, clinical management will be supported by computerised ST waveform assessment and will be guided by the STAN-guidelines, indicating when intervention is recommended. In case of poor signal quality of the foetal ECG-signal it is allowed to perform a FBS in the first stage of labour. From each woman, we will systematically (by protocol) document demographics and medical history, as well as CTG analysis, foetal ST-analysis and FBS results. Finally, the umbilical cord artery results, the performance of an instrumental delivery and neonatal outcome until discharge from the hospital will be documented.

CTG and FBS:
In women randomised to the control group, a scalp electrode will be applied to the foetal head and connected to the conventional CTG-monitor conform routine practice of CTG monitoring. If the pH of the first measurement is below 7,20 delivery is recommended unless the cause of foetal distress can be alleviated. If the pH is between 7,20 and 7,25 FBS will be repeated after 30 minutes. If the pH is above 7,25 FBS is repeated according to CTG pattern according to the attending doctor or midwife. The number of failed FBS will be recorded.

CTG and ST-analysis:
In women randomised to the index group, a scalp electrode will be applied to the foetal head and connected to the STAN-monitor conform routine practice of CTG monitoring. This electrode will allow both standard foetal heart rate monitoring (CTG) as well as ST-analysis. The CTG will be classified as normal, intermediate, abnormal or preterminal according to the FIGO-guidelines for foetal heart rate monitoring. The ST log automatically alerts the attending doctor or midwife if a significant ST-event occurs. Delivery is recommended when there are significant ST-changes unless the cause of foetal distress can be alleviated. It is only allowed to perform FBS in the CTG + ST-analysis arm in case of poor signal quality of the foetal ECG in combination with an intermediate or abnormal foetal heart rate pattern in the first stage.

Power calculation information added as of 16/07/2007:
The sample size calculation is based on the primary endpoint, which is metabolic acidosis in the umbilical cord artery.

Although in the two randomised trials the incidence of metabolic acidosis decreased from 1.5% to 0.5% in favour of the CTG + ST-analysis group, we assume that the incidence of metabolic acidosis in our higher-risk population (women delivering in the hospital with a medical indication) is higher and estimated on 3.5%, as found in our preliminary study. Based upon the numbers of the largest clinical trial with a relative risk of 0.5 the required sample size would then yield 2400 cases (1200 per arm), using an alpha of 0.05 (2-sided) and a power of 0.80. However, soon after the start of our study a third randomised clinical trial appeared, although much smaller and non-significant, but yielding an opposite effect . A meta-analysis of the three clinical trials showed the varying relative risks of 0.5, 0.4 and 2.4. Hence, to be conservative we used the meta-analysis overall relative risk of 0.6 for our power calculation, implying a reduction of metabolic acidosis, in favour of ST-analysis, from 3.5% to 2.1%. With an alpha of 0.05, a two-sided test (given conflicting results in the literature) and a power of 0.80, about 4638 women should be randomised (2319 per arm). Accounting for 10% loss to follow-up, the study requires inclusion of about 5100 women in order to obtain 4638 analysable cases.

As of 06/01/2009 this record was amended to include the following information: The inclusion of participants for this trial is complete.

Intervention type



Not Applicable

Drug names

Primary outcome measure

Presence or absence of metabolic acidosis defined as a pH less than 7.05 and a BDecf greater than 12 mmol/l in the umbilical cord artery.

There are no interim analyses, only by the data safety monitorings committee for serious adverse events.

Secondary outcome measures

1. Instrumental delivery rate for the following indications: foetal distress, failure to progress or a combination of these
2. Cost-effectiveness of both strategies: the ratio of incremental costs and the reduced rate of metabolic acidosis, associated with the strategies
3. Neonatal outcome defined by low Apgar scores, defined as less than four after one minute and/or less than seven after five minutes
4. Need for admission to the neonatal medium or intensive care unit
5. Cost-effectiveness of both monitoring strategies across hospitals, particularly, comparing academic and non-academic hospitals

There are no interim analyses, only by the data safety monitorings committee for serious adverse events.

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Women in labour
2. Singleton foetus in vertex position
3. Gestational age more than 35 + 6 weeks of gestation
4. Indication for electronic foetal monitoring (CTG)

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Women with a foetus in breech position
2. Women with twin pregnancy
3. No informed consent

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

University Medical Centre Utrecht
3508 GA

Sponsor information


University Medical Centre Utrecht (UMCU) (Netherlands)

Sponsor details

P.O. Box 85500
3508 GA

Sponsor type




Funder type

Research organisation

Funder name

The Netherlands Organisation for Health Research and Development (ZonMw) (Netherlands)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Basic results (scientific)

Publication list

1. 2007 protocol in
2. 2010 results in
3. 2012 results in

Publication citations

  1. Results

    Westerhuis ME, Visser GH, Moons KG, van Beek E, Benders MJ, Bijvoet SM, van Dessel HJ, Drogtrop AP, van Geijn HP, Graziosi GC, Groenendaal F, van Lith JM, Nijhuis JG, Oei SG, Oosterbaan HP, Porath MM, Rijnders RJ, Schuitemaker NW, Sopacua LM, van der Tweel I, Wijnberger LD, Willekes C, Zuithoff NP, Mol BW, Kwee A, Cardiotocography plus ST analysis of fetal electrocardiogram compared with cardiotocography only for intrapartum monitoring: a randomized controlled trial., Obstet Gynecol, 2010, 115, 6, 1173-1180, doi: 10.1097/AOG.0b013e3181dfffd6.

  2. Results

    Schuit E, Kwee A, Westerhuis ME, Van Dessel HJ, Graziosi GC, Van Lith JM, Nijhuis JG, Oei SG, Oosterbaan HP, Schuitemaker NW, Wouters MG, Visser GH, Mol BW, Moons KG, Groenwold RH, A clinical prediction model to assess the risk of operative delivery., BJOG, 2012, 119, 8, 915-923, doi: 10.1111/j.1471-0528.2012.03334.x.

  3. Westerhuis ME, Moons KG, van Beek E, Bijvoet SM, Drogtrop AP, van Geijn HP, van Lith JM, Mol BW, Nijhuis JG, Oei SG, Porath MM, Rijnders RJ, Schuitemaker NW, van der Tweel I, Visser GH, Willekes C, Kwee A, A randomised clinical trial on cardiotocography plus fetal blood sampling versus cardiotocography plus ST-analysis of the fetal electrocardiogram (STAN) for intrapartum monitoring., BMC Pregnancy Childbirth, 2007, 7, 13, doi: 10.1186/1471-2393-7-13.

Additional files

Editorial Notes