Efficacy of Bicarbonate on the Risk of Assisted Delivery in Nulliparous Women With Prolonged Labour (ProLabour)

January 8, 2026 updated by: Nanna Maaløe, Copenhagen University Hospital, Hvidovre

Efficacy of Bicarbonate on the Risk of Assisted Delivery in Danish Nulliparous Women With Prolonged Labour: a Double-blinded Parallel Randomized Controlled Trial (The ProLabour Trial)

The goal of this clinical trial is to learn if oral bicarbonate can treat prolonged labour in nulliparous women with prolonged labour.

The main question it aims to answer is: Do oral bicarbonate and restrictive oxytocin use reduce assisted delivery rate (emergency cesarean and vacuum/forceps delivery) in nulliparous women with prolonged labour.

Researchers will compare bicarbonate and placebo (a look-alike substance that contains no drug) to see if bicarbonate works to treat prolonged labour.

Participants will:

  • drink bicarbonate or placebo
  • have cervical dilatation reassessed after 2 hours. If still slow progression, they will follow standard protocol for oxytocin augmentation
  • will receive a questionnaire 1 month post partum to assess birth experience

1/3 of participants will have amniotic fluid lactate measured at inclusion and after 2 hours

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

1520

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Age ≥18 years.
  • Danish or English speaking.
  • Cephalic presentation.
  • Gestational age ≥34+0 - <42+0 (days +weeks) at onset of labour.
  • Normal foetal heart rate pattern in the 20 minutes prior to inclusion.
  • Spontaneous onset of labour or non-medical induced labour (balloon catheter and/or artificial rupture of membranes).
  • Active first stage of labour confirmed, according to Danish national guidelines: Cervical dilatation at ≥4 - <10 cm with regular painful contractions.
  • Prolonged labour diagnosed, according to Danish national guidelines: Cervical dilatation progresses at less than 2 cm over a 4-hour period.

Exclusion Criteria:

  • Clinical suspicion of infection (2 confirmed temperatures ≥38.5°C with epidural, ≥38 °C without epidural, or broad-spectrum antibiotics initiated)
  • Significant medical comorbidity in the form of renal or heart condition, assessed case-by-case basis.
  • Serious obstetric complication
  • Known allergy or intolerance to sodium bicarbonate.
  • Ingestion of sodium bicarbonate in active labour prior to inclusion.
  • Current treatment with following medicines: Gabpabpentin, Tetracycline, Ketoconazole (NB! These medications are already generally advised contradicted against induring pregnancy)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Sodium bicarbonate
Participants receive oral sodium bicarbonate 4.26 gram once.
Drug: Sodium bicarbonate
4,26 gram given once.
Placebo Comparator: Placebo
Participants receive placebo once.
Drug: Placebo
Placebo given once.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Difference in incidence of assisted delivery
Time Frame: At birth
Defined as a composite of emergency caesarean section and instrumental vaginal delivery
At birth

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Difference in adverse neonatal outcome
Time Frame: From birth until 7 days postpartum
Composite of perinatal adverse outcomes within the first 7 days of life, including perinatal mortality and neonatal morbidity. Neonatal morbidity is defined as arterial umbilical cord pH <7.10, resuscitation (bag and mask or intubation), hypoxic ischemic encephalopathy II-III, intracranial haemorrhage, neonatal seizures, meconium aspiration syndrome, and admission to a neonatal unit.
From birth until 7 days postpartum
Difference in total oxytocin dose
Time Frame: Intrapartum
Administered intrapartum for augmentation.
Intrapartum
Difference in duration of active labour
Time Frame: Intrapartum
From diagnosis of active labour until childbirth
Intrapartum
Difference in amniotic fluid lactate (AFL) concentration
Time Frame: Measured at inclusion and two hours later.
Collected in the labourroom and analysed externally. Attending clinicians will not know the AFL.
Measured at inclusion and two hours later.
Difference in intra- or postpartum infection
Time Frame: Intrapartum and until 7 days postpartum
2 confirmed temperatures ≥38.5°C with epidural, ≥38 °C without epidural, or broad-spectrum antibiotics.
Intrapartum and until 7 days postpartum
Difference in epidural analgesia
Time Frame: Intrapartum
As documented in the case records
Intrapartum
Difference in number of women getting antibiotics during labour
Time Frame: Intrapartum
As documented in the case records.
Intrapartum
Difference in postpartum blood loss
Time Frame: From birth until 24 hours postpartum
Visual assessment estimated by the attending midwife or calculated using a weight if suspected postpartum haemorrhage.
From birth until 24 hours postpartum
Difference in women receiving tocolytics used during labour
Time Frame: Intrapartum
Recorded in the case records
Intrapartum
Difference in number of 3rd or 4th-degree perineal tears
Time Frame: Within 2 hours after birth
Assess by the midwife/doctor suturing the tear.
Within 2 hours after birth
Difference in birth experience
Time Frame: One month postpartum
Patient reported using Childbirth Experience Questionnaire (CEQ) which uses a 4-point Likert scale and higher scores indicate a more positive experience.
One month postpartum

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Copenhagen University Hospital, Hvidovre

Collaborators

Aarhus University Hospital
Rigshospitalet, Denmark
University of Copenhagen
University of Amsterdam
University of Liverpool
Copenhagen Trial Unit, Center for Clinical Intervention Research

Investigators

  • Principal Investigator: Nanna Maaløe, PhD, University of Copenhagen

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

February 1, 2026

Primary Completion (Estimated)

January 31, 2028

Study Completion (Estimated)

January 31, 2028

Study Registration Dates

First Submitted

December 22, 2025

First Submitted That Met QC Criteria

December 22, 2025

First Posted (Estimated)

January 7, 2026

Study Record Updates

Last Update Posted (Estimated)

January 12, 2026

Last Update Submitted That Met QC Criteria

January 8, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2024-0338

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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