Although Hyoscine N butyl bromide (HBB) is used liberally to facilitate cervical dilatation, there is little and inconclusive data about its efficacy. The aim of this study was to determine the efficacy and safety of HBB on the augmentation of labor.420 of total 1640 pregnant women admitted to the investigators clinic (Sisli Ethal Training and Research Hospital, Obstetrics and Gynecology Department Obstetrics Service ) between 37-41 gestational weeks, active phase (cervical dilatation: 4 cm, cervical effacement: %50 or more) of spontaneous labor with vertex presentation enrolled to study. 382 of them were included in this study. Patients were randomized to receive intravenously(IV) either 20 mg/ml HBB or a similar amount of placebo (1 ml 0.9% NaCl) at the beginning of the active phase of labor. The medications applied as single dose. The time elapsed until the second stage of labor, second stage and third stage were measured.

The investigators aimed to study the effects and safety of 20mg intravenous HBB for the shortening of labor in both prima- and multigravid women.The study designed as a double blind, randomized, controlled trial comparing the two groups of intervention; Intravenous 20 mg (1mL) Hyoscine-N-Butylbromide (HBB) versus placebo (1mL saline) in both primigravid and multigravid women.Singleton, vertex presentation at term (gestational age range; 37-41weeks) primigravid and multigravid women without any chronic and pregnancy-induced diseases were included to the study. The investigators excluded the cases with premature rupture of membranes, preeclampsia, eclampsia, placental abruption, placenta previa, abnormal placental attachment, twin pregnancy, non- cephalic presentations, previous uterine surgery and cephalopelvic disproportion.Randomization was done by using cards .The women were allocated into two groups by using a sealed enveloped system.A yellow and a red card were placed separately in each sealed envelope. The syringes containing the drug and placebo were prepared by the investigational pharmacy staff and labeled with a yellow or red sticker on it. Each syringe contained either 1ml(20mg) of Hyoscine-N-Butylbromide (HBB) (MOLIT ampule,Adeko, Turkey) or 1 ml of normal saline solution (placebo) in which both of the liquids are colorless. The participants, nurses and doctors were all blinded to syringes. The patients were asked to pick up one envelope in order and the color of the card was corresponding to the sticker's color on the syringe.Nurses applied the selected color labeled syringe to each patient. Participants received the contents of the syringe as a single dose, given intravenously (IV).

A partogram was drawn and vaginal examinations recorded in every 2 hours.The active phase of labor was defined as 4 cm cervical dilatation and 50% cervical effacement in the presence of regular uterine contractions (2-3 contractions in every 10 minutes). The drug was given only once when the active phase was achieved. Iatrogenic amniotomy was performed for women who did not have a spontaneous rupture of membrane at the time when the cervical ripening was 8 cm. The duration of labor during the first, second and third stages, oxytocin induction, iatrogenic amniotomy, pre- and postpartum haemoglobin levels, birth weight and APGAR scores were recorded. Neonatal APGAR scores were determined 1 and 5 minutes after birth.

Inclusion Criteria:

• Singleton, vertex presentation at term (gestational age range; 37-41weeks) primigravid and multigravid women without any chronic and pregnancy-induced diseases

Exclusion Criteria:

• The cases with premature rupture of membranes, preeclampsia, eclampsia, placental abruption, placenta previa, abnormal placental attachment, twin pregnancy, non- cephalic presentations, previous uterine surgery and cephalopelvic disproportion