In this study, parturients will be randomized to either internal or external tocodynamometry contractions' follow up. Investigators recruit primiparous, those who try to have vaginal birth after cesarean section and multiparous, who need oxytocin during labor. Primary endpoint is the number of operative labors in each group. Secondary endpoints are the duration of labor, the use of oxytocin and the condition of the newborn.

Inclusion Criteria:

• gestational age ≥ 37 weeks
• singleton pregnancy
• a fetus in cephalic position
• normal cardiotocograph in the time of randomization
• cervical ripening < 7 cm
• either 1) primipara, 2) multipara, who needs oxytocin during first stage of labor or 3) parturients with previous cesarean section

Exclusion Criteria:

• parturient with hepatitis or HIV or other significant viral infection
• Acute infections (fever over 37,5, or C-reactive protein over 20) in the time of randomization
• Estimated fetal weight over 4,5 kg
• Suspected fetal abnormality