Study design
This parallel randomized study examined two methods of management of the third stage of labor in low-risk pregnant women. The Najafabad Islamic Azad University Branch approved the study (IR..IAU.NAJAFABAD.REC.1396.39). All participants signed informed consent at admission.
Participants
All pregnant women attending three teaching hospitals for delivery in Isfahan, Iran, in 2017 were approached during one complete calendar year. Of these, women were entered into the study if they satisfied the inclusion criteria. The inclusion criteria were singleton pregnancy, term pregnancy (gestational age 37 complete weeks confirmed by certain last mensural period-LMP, or early ultrasound), expected to have a spontaneous vaginal delivery, pregnancy with vertex presentation, absence of placental abnormalities, and fetal congenital anomalies by prenatal ultrasound examination, no maternal obstetric or medical complication such as placental abruption, low lying placenta, oligohydramnios and polyhydramnios, chorioamnionitis, history of prolonged labor (baby is not born after approximately 20 hours of regular contractions), instrumental delivery (vacuum, forceps), antepartum hemorrhage (bleeding from or into the genital tract, occurring from 24 weeks of pregnancy and prior to the birth of the baby), eclampsia and preeclampsia. During the labor, the amount of serum and drugs received, and the length of the first and second stages of labor were recorded. The length of the first and second stages was recorded as a period of hospitalization. In the case of prolonged delivery, instrumental delivery, known coagulation disorders in the mother, and receiving analgesic drugs or anesthesia during labor, the woman was excluded from the study. Cases with a thick size placenta (more than 4 cm) also were excluded.
Procedure
For all women, active management was used for expulsion of the placenta. After delivery of the fetus-20 units of oxytocin were injected into 1000 ml of lactated ringer’s solution and injected at a speed of 20 ml/min (200 mU/min) for a few minutes until the uterus remained firmly contracted and then was reduced to 2 mL/min until the mother was ready for transfer from the recovery suite to the postpartum unit [10]. The next step was clamping and cutting the umbilical cord. To this end, the control group did not receive any other interventions, and we only calculated the time from cutting the umbilical cord to the full delivery of the placenta. However, for the drainage group, after cutting the umbilical cord, the clamp of the umbilical cord was opened and allowed to drain blood until flow ceased. Recording the time was exactly the same as the previous step. After signs of placental separation, which were a sudden gush of blood into the vagina, a globular and firmer fundus, a lengthening of the umbilical cord as the placenta descends into the vagina, and elevation of the uterus into the abdomen [10], the delivery of the placenta was done by Brandt-Andrews maneuver and encouraging mother to push. This is a technique for expelling the placenta from the uterus during the third stage of labor. One hand puts gentle traction on the cord while the other presses the anterior surface of the uterus backward. After the expulsion of the placenta in both groups, a complete and accurate examination of the placenta and membranes was performed. As such, we checked the uterus regarding the retained placental cotyledon or membranes. In the absence of a placenta expulsion within 30 minutes (retained placenta) [11] or there was suspicion for the retained portions of placenta and membranes after spontaneous separation or in the event of hemorrhage and the necessity of the placenta removal before 30 minutes, it was removed manually. For postpartum hemorrhage after delivery of the placenta and the first 2 hours that the mother was in the recovery unit, we looked at the blood flow from the mother’s vaginal area during the massage of the uterus. We marked bleeding in the checklist as mild, moderate, or severe.
Outcome measures
Outcome measures included recording the length of the third stage of labor, the incidence of placental retention, the manual removal of the placenta, and postpartum hemorrhage. The recording was carried out by a fellow researcher who was blind to the study.
Sample size
The following formula was used to estimate the sample size.
$$n=\left(\frac{2\Big({z}_{\alpha /2}+{z_{1-\beta }\Big)}^{2}\times {\sigma}^2}{\varepsilon^2}\right)$$
As such, for a study with an 80% power at 5% significance level and considering precision (ε) by a quarter of the standard deviation (σ), we estimated that the study would require at least 198 pregnant women per each group. The value for Zα/2 = 1.96 and Z1-β = 0.842 (for 5% significance level and power 80%) are 1.96 and 0.842, respectively. However, in practice, we included 200 women per each group.
Randomization
Randomization was done in the delivery room. During the data collection period, the study coordinator was responsible for introducing women to the midwife on arrival at the delivery room. The randomization was performed by a midwife who was not involved in the study as a member of the research team. She randomly assigned one pre-marked card to each woman to determine the study groups (intervention or control). The sequence was continued until the required sample size was achieved.
Statistical analysis
Descriptive statistics, including frequencies, means, and standard deviations, were used to describe the demographic and clinical data. In addition, chi-square, independent samples t-test, the Fisher’s exact test, and Mann-Whitney U test (where necessary) were used for comparison. To control for the baby’s weight, an analysis of covariance was used to compare the length of the third stage between the two groups. To compare delivery outcomes chi-square and the Fisher’s exact tests were applied. In all instances, the level of statistical significance was set at p < 0.05.
