A case control study conducted on 120 women coming to Cairo University Maternity Hospital .Patients who meet the inclusion criteria were asked to participate in the study and a verbal consent was obtained from each patient. Patients will be divided into three equal groups (A, B, C). A single dose of the drug (placebo or HBB 20mg or HBB 40 mg) will be injected intravenously slowly to groups A, B, C respectively. Labouring mothers will be monitored in bed. Vaginal examination will be conducted every two hours. The duration of the first stage was calculated from the time of cervical dilatation of three to four centimeters in active labour until a fully dilated cervix will be observed

A case control study conducted on 120 women coming to Cairo University Maternity Hospital .Patients who meet the inclusion criteria were asked to participate in the study and a verbal consent was obtained from each patient. Patients will be divided into three equal groups (A, B, C). A single dose of the drug (placebo or HBB 20mg or HBB 40 mg) will be injected intravenously slowly to groups A, B, C respectively. Labouring mothers will be monitored in bed. Vaginal examination will be conducted every two hours. The duration of the first stage was calculated from the time of cervical dilatation of three to four centimeters in active labour until a fully dilated cervix will be observed

Inclusion Criteria:

1. Age: 18 - 35 years old
2. Primigravdae.
3. Gestational age between completed 37- 41 weeks + 6 days.
4. Uncomplicated cephalic singleton pregnancy occipto-anterior position.
5. Established spontaneous active labour (defined as the presence of at least three regular uterine contractions over 10 minutes with cervical dilatation three to four centimeters) with cervical effacement not less than 50%.
6. Intact amniotic membranes.

Exclusion Criteria:

1. Multigravidae.
2. Multiple fetus.
3. Malpresentation.
4. Patients with indications of elective caesarean section.
5. Medical conditions associated with pregnancy e.g. preeclampsia, diabetes mellitus.
6. Contraindications for hyoscine butylbromide which include known allergy to hyoscine or other atropinics (e.g., atropine, scopolamine), myasthenia gravis, megacolon or glaucoma.
7. Patients presented to causality with spontaneous rupture of membranes.
8. Spontaneous rupture of membranes during the active phase of first stage of labour.
9. Oxytocin induction or augmentation.
10. Patients who underwent epidural anesthesia or other types of analgesia.