Massage by an electric massage chair compared to nitrous oxide gas as first-line pain relief in labour

INTERVENTION: Participants who have provided informed written consent will be randomised in a 1‐to‐1 ratio. Randomisation will be effected by opening the lowest numbered sealed opaque envelope available to reveal the allocated intervention for the latest recruit. The randomisation sequence is generated in random blocks of 4 or 8 using an online randomiser by an investigator not involved in the recruiting. Due to their obvious nature, no attempt will be made to mask the interventions. As a first‐line analgesic in labour, randomisation to: 1. Application of mechanical massage using the electric massage chair (active intervention) [Participants randomised to the use of an electric massage chair are instructed to sit in the massage chair with the ‘full‐body’ massage program switched on for at least 30 minutes. They can continue to use the chair for as long as they want until the active second stage of labour.] OR 2. Application of nitrous oxide gas (Entonox) inhalation (control intervention) [Participants randomised to nitrous oxide gas inhalation through a mouthpiece are instructed on its use; holding the mouthpiece themselves, putting their lips around the flat, white tube, making an air‐tight seal, and taking slow deep breaths, starting just as a contraction begins. Once the contraction is over, the mouthpiece can be removed to breathe room air. They can continue to use the nitrous oxide for as long as they want until the active second stage of labour.] Participants may request stronger analgesics including opioids and an epidural on their perception of need or medically advised due to developments in labour. CONDITION: First‐line labour pain relief in nulliparas ; Pregnancy and Childbirth PRIMARY OUTCOME: 1. Additional analgesic in labour (from the medical record); 2. Maternal satisfaction with their allocated first‐line pain reliever (by Numerical rating scale [NRS] 0‐10, completely dissatisfied to completely satisfied ‐ asked after the delivery) SECONDARY OUTCOME: 1. Pain score (by NRS 0‐10, a higher score denoted greater pain – asked at 30, 60 and 120 minutes) ; 2. Time from intervention start to time of (from the medical record):; 2.1. initiation of other labour analgesia (if any); 2.2. initiation of epidural (if any); 2.3. second stage of labour; 2.4. delivery; 3. Epidural analgesia during labour (from the medical record); 4. Opiate analgesia during labour (from the medical record); 5. Side effects during labour (asked after delivery); 5.1. Vomiting; 5.2. Dizziness; 5.3. Drowsiness; 5.4. Back pain; 5.5. Body pain; 5.6. Back bruising; 6. Mode of delivery (from the medical record); 7. Indication for operative delivery (from the medical record); 8. Perineal condition after delivery (from the medical record); 9. Estimated delivery blood loss (from the medical record); 10. Fever (from the medical record); 11. Birthweight (from the medical record); 12. Apgar score at (from the medical record) 1 minute and 5 minutes; 13. Umbilical cord artery blood (from the medical record):; 13.1. pH; 13.2. base excess; 14. Neonatal admission (from the medical record); 15. Indication for admission (from the medical record); 16. For first‐line labour pain relief in the future, I prefer to use (Asked after delivery): ‐Massage chair OR Nitrous oxide (Gas – Nitrous oxide) INCLUSION CRITERIA: 1. Admitted to the ward for birth (for labour or induction of labour) 2. Planned vaginal delivery 3. Accepts either nitrous oxide or massage chair as first‐line labour analgesia 4. Nulliparous (no prior delivery > 20 weeks) 5. Age = 18 years 6. Gestational age of = 37 weeks 7. Singleton pregnancy 8. Cephalic presentation 9. Reassuring fetal heart rate tracing 10. Estimated fetal weight of 2 to 4 kg 11. Requesting labour pain relief