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NCT Number: NCT07321379

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

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

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Key information

Conditions

Prolonged Labor Dystocia Female Urogenital Diseases and Pregnancy Complications Labor Dystocia Obstetric Labor Complications Pregnancy Complications Urogenital Diseases

Age range

18 year–50 year

Sex eligibility

Female

Study type

Interventional

Phase

Not applicable

Primary location

Aarhus University Hospital, Aarhus, Denmark

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Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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)

Treatment and study plan

Sodium bicarbonate

Drug

4,26 gram given once.

Placebo

Drug

Placebo given once.

Primary outcomes

  1. Difference in incidence of assisted delivery

    Time frame: At birth

    Defined as a composite of emergency caesarean section and instrumental vaginal delivery

Secondary outcomes

  1. 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.

  2. Difference in total oxytocin dose

    Time frame: Intrapartum

    Administered intrapartum for augmentation.

  3. Difference in duration of active labour

    Time frame: Intrapartum

    From diagnosis of active labour until childbirth

  4. 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.

  5. 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.

  6. 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.

  7. Difference in epidural analgesia

    Time frame: Intrapartum

    As documented in the case records

  8. Difference in number of women getting antibiotics during labour

    Time frame: Intrapartum

    As documented in the case records.

  9. 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.

  10. Difference in women receiving tocolytics used during labour

    Time frame: Intrapartum

    Recorded in the case records

  11. 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.

Study contacts

Contact information is provided by the study sponsor or research team.

Nanna Maaløe, PI, PhD

CONTACT

[email protected]

+4541271984

Nina Olsén Nathan, Co-PI, PhD

CONTACT

[email protected]

+4553670600

Sponsors and collaborators

Lead sponsor

Copenhagen University Hospital, Hvidovre

Other

Collaborators

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

Registry information

Official study title

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)

Acronym: ProLabour

Important dates

Study start
2026
Primary completion
2028
Study completion
2028
First posted
Jan 7, 2026
Registry last updated
Jan 12, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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