Inclusion criteria:
Nulliparous women during labor with alive singleton fetus at gestational age of 37-41 weeks,
Aged 18 years or more,
Body mass index of 18.5-30 kg/m2,
Cephalic presentation of the fetus,
Bishop score of 6 or more with cervical dilatation of 4-6 cm,
Prolonged labor: progress of cervical dilatation less than 1 cm/h for 3 h or dilatation arrest for 2 h, with weak uterine contractions (less than 3 contractions in 10 min),
Intact amniotic sac or a maximum of 30 min from its rupture,
Normal cardiotocogram at the time of admission and recruitment.
Exclusion criteria:
History of any incisions on the uterus,
Abnormal pelvic dimensions,
Abnormal bleeding,
Any abnormalities in the genital soft or bone tissue,
History of infertility and use of any assisted reproductive techniques in the present pregnancy,
Any genital tract infection interfering with vaginal delivery (including genital herpes, fever with unknown cause, ...),
Maternal medical illness (diabetes, high blood pressure, heart diseases, epilepsy, ...),
Abnormal volume of amniotic fluid,
Sustained asynclitisme or persistant posterior position,
Severe fetal scalp edema or molding,
Estimated fetal weight of more than 4000 g
Known severe fetal anomalies interfering with vaginal delivery (hydrocephalus, polycystic kidney and any large abdominal mass) diagnosed,
Fetal intrauterine growth restriction (IUGR),
Maternal speech, hearing and visual problems.