Inclusion criteria:
Mother's desire to vaginal delivery
A single fetus with a view of the apex of the head
Gestational age Between 37 to 41 weeks
The regularity of the fetal heartbeat with a number of 120-160 beats per minute
The mother's vital signs are normal
having minimum reading and writing literacy
Dilatation 4-5 cm
Having at least 2 to 3 spontaneous uterine contractions lasting 40-45 seconds within ten minutes
Having less than 4 vaginal deliveries
Body mass index 20-30 kg/m2
The fit of the fetal head with the mother's pelvis based on clinical examination
The estimated weight of the fetus 2500-4000 grams
Proportionality of uterine height with gestational age in clinical examination
The normality of the number of fetal movements according to the mother's report or the reaction of the result of the non stress test
Mother's age between 18-35 years
Exclusion criteria:
The presence of medical and obstetrical problems in the current pregnancy
Addiction to tobacco, drugs and alcohol drinks
Height less than 145 cm
The existence of any obstacles to vaginal delivery
Existence of maternal or fetal risk factors
The existence of contraindications for back massage (lumbar disc herniation, skin diseases, fever, etc.)
The existence of contraindications to the use of Entonox (mother's inability to hold the mask, maxilla and facial fractures, impaired consciousness and intoxication, impaired oxygen supply, upper respiratory tract infection or respiratory disease, nasal deviation, chronic obstructive pulmonary disease, receiving large amounts of intravenous narcotics, vitamin B12 deficiency and mothers treated with vitamin B12, maxillofacial surgery in the last month, inner ear obstruction, fetal distress, unstable hemodynamic status, some heart diseases such as pulmonary hypertension, problematic airway, fullness of the mother's stomach and schizophrenia)