Shnaw Abdulwahab Karim a, and Rozhan Yassin Khalil b


a Sulaimani Maternity Teaching Hospital, Sulaimani, Kurdistan Region, Iraq.

b Sulaimani Maternity Teaching Hospital, College of Medicine,University of Sulaimani, Kurdistan Region, Iraq,

Submitted: 12/7/2021; Accepted: 16/3/2022; Published: 21/6/2022

DOI Link: https://doi.org/10.17656/jsmc.10352 



Labour pain is one of the acute severe pains women suffer during their lives. Various methods have been tried to manage it.


The aim was to compare analgesic effects and outcomes of Entonox versus Pethidine for labour pain.

Patients and Methods

The non-blinded Randomised clinical trial was performed on 221 pregnant women admitted to the Labor Ward of Sulaimani Maternity Teaching Hospital from January 2020 to January 2021. Women were randomly allocated the group I of 111 pregnant women who received Entonox and group II of 110 pregnant women who received 1 mg/kg of Pethidine. A visual analogue scale (VAS) pain score was used before 30 and 60 minutes after drug administration. In addition, a Neonatal Apgar score of one and five minutes was recorded.


There were no significant demographic feature differences between both groups. Mean pain scores before drugs were 7.8±1.6 and 7.8±1.3 after 30 minutes were 4.6±1.6 and 5.7±1.6, and after 60 minutes were 3.8±1.5 and 3.9±1.6 for Entonox and pethidine groups, respectively. Entonox decreased pain score better than Pethidine after 30 minutes (p-value of <0.001); however, Pethidine decreased pain score better than Entonox after 60 minutes (p-value of <0.001). Mean Apgar scores in 1st minute were 8.6±.87 and 8.41±1.28, and in 5th minute was 9.84±.37 and 9.62±.82 for Entonox and pethidine groups, respectively. Significant association of drugs with Apgar score at 5th minute was found. 


Entonox was better for acute pain management within 30 minutes; Pethidine was better for longer than 60 minutes.


Entonox; Labor Pain; Pain Relief; Pethidine; Sulaimani.


1.  Imani F, Safari S. "Pain Relief is an Essential Human Right", We Should be Concerned about It. Anesthesiol Pain Med. 2011;1(2):55–7. 

2.  Phillips CJ. Economic burden of chronic pain. Expert Rev Pharmacoeconomics Outcomes Res. 2006;6(5):591–601. 

3.  Wee MYK, Tuckey JP, Thomas P, Burnard S. The IDvIP Trial: A two-centre randomised, double-blind controlled trial comparing intramuscular diamorphine and intramuscular Pethidine for labour analgesia. BMC Pregnancy Childbirth. 2011;11:51. 

4. Mobaraki N, Yousefian M, Seifi S, Sakaki M. A randomised controlled trial comparing Entonox with Pethidine for pain relief in primigravid women during the active phase of labour. Anesthesiol Pain Med. 2016;6(4):e37420. 

5.  Rosen MA. Nitrous oxide for relief of labour pain: A systematic review. Am J Obstet Gynecol. 2002;186:S110– 26. 

6. Subasinghe T. The Effectiveness of Entonox Compared to Pethidine for Labor Pain: A Systematic Review. Proceeding 5th Int Conf Public Heal. 2019;5(2019):8–18. 

7.  JP R. Safety and Risks of Nitrous Oxide Labor Analgesia: A Review. J Midwifery Women's Heal. 2011;56:557–65. 

8. King TL, Wong CA. Nitrous oxide for labour pain: Is it a laughing matter? Anesth Analg. 2014;118(1):12–4. 

9. Bishop JT. Administration of Nitrous Oxide in Labor: Expanding the Options for Women. J Midwifery Women's Heal. 2007;52:308–9. 

10. Collins MR, Starr SA, Bishop JT, Baysinger CL. Nitrous oxide for labour analgesia: expanding analgesic options for women in the United States. Rev Obstet Gynecol. 2012;5(3):126–31. 

11. Manouchehrian N, Bakhshaei MH. Nitrous oxide relieves anxiety and pain in parturients under spinal anaesthesia for caesarean section. Anesthesiol Pain Med. 2014;4(2):e16662. 

12. Anderson D. A Review of Systemic Opioids Commonly Used for Labor Pain Relief. J Midwifery Women's Heal. 2011;56:222–39. 

13. Sosa CG, Buekens P, Hughes JM, Balaguer E, Sotero G, Panizza R, et al. Pethidine's effect during the first labour stage on the acid-base status at birth. Eur J Obstet Gynecol Reprod Biol. 2006;129:135–9. 

14. Goodson C, Martis R. Pethidine: to prescribe or not to prescribe? A discussion surrounds Pethidine's place in midwifery practice and New Zealand prescribing legislation. New Zeal Coll Midwives J. 2014;49:24. 

15. Haefeli M, Elfering A. Pain assessment. Eur Spine J. 2006;15(SUPPL. 1):17–24. 

16. Rooks JP. Nitrous oxide for pain in labour - Why not in the United States? Birth. 2007;34(1):3–5. 

17.  addy SC, Garlick SR. A systematic review of the safety of analgesia with 50% nitrous oxide: Can lay responders use analgesic gases in the prehospital setting? Emerg Med J. 2005;22(12):901–6. 

18. Teimoori B, Sakhavar N, Mirteimoori M. Nitrous Oxide versus Pethidine with Promethazine for Reducing Labor Pain. Gynecol Obstet. 2011;01(01):1–4. 

Full Text

 © The Authors, published by University of Sulaimani, College of Medicine

This work is licensed under a Creative Commons Attribution 4.0 International License.