This study aims to evaluate the effect of meperidine on the length of active phase of labor in nulliparous or multiparous women, who will be randomized into two (control and study) groups. Our hypothesis is that the use of meperidine during active labor has no effect on the duration of labor.

• Our aim is to examine the effect of the opioid derivative meperidine used during labor on the duration of labor in singleton pregnancies.
• The sample size was calculated using the Number Cruncher Statistical System (NCSS) / PASS 2007. Power 80% and significance level (α) 0.05, the mean (mean) ± standard deviation (SD) of the first 20 individuals included in the control group of the study (296.04 ± 170.02) and has minimal clinical significance for the active phase of labor from previous studies. We found that the sample size should be 200 (100/100) considering the duration (30 minutes).
• A Simple randomisation using a random-number table was performed by the independent nurse staff, who took no further part in the study.Using the sealed envelope technique, parturients were randomly allocated to two groups: A meperidine group and B normal saline group
• Age, height, weight, body mass index (BMI), gravida, parity, week of gestation, expected fetal weight (EFW), hemoglobin (Hb) and hematocrit (Hct) values and episiotomy requirements were recorded in two groups.Gender, birth weight, 1st and 5th minute Apgar scores and presence of meconium aspiration of the newborns in two groups were recorded.
• During labor, oxytocin induction was not performed during the latent phase in accordance with the routine protocol of our hospital. Pregnant women in both groups were given oxytocin (Synpitan® amp) at a concentration of 1% by 10 drops/min by performing amniotomy when Bishop score was 6 or cervix dilation was 4 cm and when 70% effacement was achieved. In the meperidine group, when the cervical opening was 6 cm and 70% washout, 25 mg iv bolus injection of meperidine (2.5 ml) was administered. The same amount (2.5 ml) of physiological saline was administered intravenously to the subjects in the control group. The patients were followed in NST until 10 cm clearance and 100% effacement. This time was recorded as active phase time. The time from the end of the active phase period to the birth of the baby was recorded as the duration of the second phase of birth.
• The primary outcome of interest in this study is the duration of active phase of labor .

Inclusion Criteria:

• gestational age between 38 and 42 weeks
• live fetus
• cephalic presentation
• in active phase of labour

Exclusion Criteria:

• placenta previa, placental abruption
• caesarean section or any uterine scarring
• multiple gestation
• fetal macrosomia (≥4000 g)
• meperidine allergy
• use any kind of labour induction or augmentation before on admission for delivery in our hospital

term pregnancies with active labor

24h

Both drug provider and patient do not know which drug or placebo was given