Shahnaz Ahmadi - Department of Gynecology Oncology, School of Medicine, Iran University of Medical Science, Tehran, Iran
Katayoon Farahani - Department of Gynecology Oncology, School of Medicine, Iran University of Medical Science, Tehran, Iran
Majid Aklamli - Department of Anesthesiology, School of Medicine, Iran University of Medical Science, Tehran, Iran
Kambiz Ahmadi - Department of Computer Sciences ,School of Mathematical Science, Shahrekord University, Shahrekord, Iran
Niloufar Beheshti - Department of Gynecology Oncology, School of Medicine, Iran University of Medical Science, Tehran, Iran

Background & Objective: Spinal analgesia and Entonox analgesia are used as pain relief methods during labor. This cross-sectional study was conducted to determine the effect of spinal analgesia and Entonox analgesia on the duration of the first, second, and third stages of labor, Apgar score, and maternal and fetal outcomes. Materials & Methods: Clinical information of ۱,۰۰۰ patients who delivered at Shahid Akbarabadi Hospital and underwent painless delivery with Entonox gas and spinal anesthesia was assessed; then, according to the inclusion criteria, ۲۸۰ cases were divided into two groups: the spinal analgesia group (n=۱۴۰) and Entonox analgesia group (n=۱۴۰). In the spinal analgesia group, ۲۵ μg of fentanyl and ۱-۲ mg of bupivacaine were administered. For the Entonox group, Entonox inhalation was administered via a face mask at the initiation of pain at each contraction. The duration of labor, mode of delivery, side effects, and maternal satisfaction were also compared in the two groups. Results: The duration of the first stage was significantly shorter in the spinal analgesia group than in the Entonox analgesia group (P<۰.۰۰۱), but the duration of the second stage in the spinal analgesia group was longer (P<۰.۰۰۱). There were no significant differences in the cesarean section rates, Apgar score, weight, and acidity (PH) and the partial pressure of carbon dioxide (pCO۲) between the two groups. Measured pain was significantly lower in the spinal analgesia group (P=۰.۰۱) than in the Entonox analgesia group regarding visual analog scale (VAS) scores. Conclusion: Spinal analgesia is a safe, suitable, and effective method for pain reduction with no adverse effects on the outcome of labor compared to Entonox analgesia.

Labor pain, Labor stage, Nitrous oxide, Pregnancy outcome, Spinal analgesia