Dystocia is the most common indication for primary cesarean section. The most common cause of dystocia is uterine dysfunction. In all cephalopelvic disproportion studies, more attention is usually paid on fetus and pelvic rather than on the role of uterine contraction in delivery. So we decided to determine the relationship between dystocia and uterine contraction patterns.

Inclusion Criteria:

• age 18-35 years
• singleton pregnancy with cephalic term presentation
• tendency to do vaginal delivery
• having no medical or mental diseases
• having no pregnancy complications
• Intact membranes
• BMI<26

Exclusion Criteria:

• using oxytocin before and during the monitoring of contractions
• performing cesarean section for any reason except arrested delivery or pelvic constriction
• the birth weight< 2500 or >4000
• using the analgesia such as epidural anesthesia morphine and pethidine during the study

primiparous women