Combined Intravenous Tramadol and Paracetamol Versus Intramuscular Pethidine for Pain Relief During the First Stage of Labor. Compare the Efficacy and Adverse Effects

The goal of this intervention study is to compare the efficacy and adverse effects of pain relief during the first stage of labor using 75 mg IM pethidine versus the combination of IV 100 mg tramadol and 1000 mg paracetamol. The investigator assume that the combination of IV tramadol and paracetamol will be more effective with less adverse effects than IM pethidine in pain relief at the first stage of labor. The investigator primary outcome is The effect on pain relief according to numeric rating scale (NTS) in the study groups Before the administration of the drugs, fetal heart rate patterns and contractions will be recorded with cardiotocography monitor for at least 20 min. The investigator will evaluate vigilance at 30 minutes following drug administration. NRS pain score (0-10) will be collected before administration and one hour after drug administration