Whenever the benefits of ending pregnancy before the automatic beginning of labor excel the benefits of pregnancy continuation that is the time for labor induction (1). Labor induction is a common necessity to induce labor in the absence of labor pain (2).
Common indications of labor induction include rapture of membranes without labor pain, hypertension, fetus’ unreassuring conditions and post-term pregnancies (3). Nowadays, using active labor induction is continuously increasing and labor induction is used in more than 15% of pregnancies (1). Amniotomy and induction using oxytocin are among common methods of labor induction, at the moment (4,5).
The rate of success in these methods depends on the degree of cervical ripening before induction. Cervix condition and its desirability is hugely essential for labor induction and it is not desirable enough in most of the situations where labor induction is needed. Bishop is one of the scoring methods for cervix in which the less the score, the less cervical ripening and consequently the less the possibility of successful labor induction. This also doubles the demand of cervical ripening (1).
In previous researches the Bishop score for undesirable cervix equals 4 or less which is the cervical ripening indication. Therefore, special attention has been paid to cervical ripening before the induction of labor (6).
Various methods are being used for cervical ripening which can be categorized into two general groups of medical techniques and mechanical techniques (7).
There is a risk of uterine rapture following uterine tachysystole in medical methods, therefore, there is a particular focus on mechanical methods for cervical ripening and extensive studies has been done in this area and on comparing the effects of different methods (8).
Mechanical methods are generally classified in three categories: cervical trans catheter, hygroscopic dilators including Laminaria and stripping membranes (9).
Cervical trans catheter with or without Salin infusion, causes immediate improvement of Bishop score and decreasing labor speed. Laminaria is a type of seaweed which functions as a cervical dilator in the way that it thickens gradually through absorbing moisture and dilates cervix (1).
Synthetic misoprostol is prostaglandin E1 which is used to prevent ulcer peptic in 100 and 200 microgram tablets. This product is utilized for cervical ripening and labor induction and it can be prescribed oral or vaginal (2). Its vaginal applica-tion is more effective and it has less maternal complications. It is also more economical consider-ing the fact that one 100 microgram misoprostol tablet costs less than $1 while the cost for a dose of 0.5 milligram dinoproston vaginal jell is $75. Side effects such as nausea, vomit, diarrhea, fever and cramp is also less seen while using misoprostol (3,10,11).
Prostaglandin E2 physiologically improves cervical ripening by increasing membrane mucus under the cervix and fluctuating collagen bands. It also increases uterine myometrial sensitivity to oxytocin (12).
In lots of studies, Foley catheter and prostaglandin effects have been compared in cervical ripening before labor induction. In Dalui study, Foley catheter has been more effective than prostaglandin E2 in cervical ripening before the induction of labor utilizing oxytocin (13), whereas in Saleem study prostaglandin E2 and Foley catheter were contrasted in cervical ripening before labor induction with oxytocin and no discrepancy was seen in induction duration and cesarean rate (14). In Cromi study, as well, which was a descriptive one, utilizing Foley catheter inside cervix before labor induction was found safe and effective (15). In previous clinical trials, gestational age and the number of delivery have been widely divers and different results have been gained. Cervical stretching by Foley catheter is one of the mechanical methods and utilizing misoprostol prostaglandin E2 a medical one, by the combination of which cervical ripening and labor induction is possible (16).
In a study by Jozwiak et al. vaginal misoprostol and Foley catheter placed in cervix and the combination of both methods were examined. In this study there was no difference among the three groups in terms of vaginal delivery rate and labor induction duration, delivery active phase duration and the interval between induction and the beginning of active phase. They also concluded that combining both methods is necessarily more effective on cervical ripening (17).
Studies done by other researchers also indicated similar results. Since no study has been done in Iran in this matter so far, and since it is of great importance to prevent taking medications which are not easily provided, more practical methods are required. Therefore, it was decided to do a contrasting analysis on using vaginal misoprostol on its own and cervical stretching through Foley catheter and the combination of these two methods for cervical ripening and labor induction. If the same results of the above-mentioned studies are gained, it suffices to stretch the cervix in such cases (15).
Particular attention has been paid to mechanical methods for cervical ripening since there are the risks of uterine rapture following possible tachysystole, fetal distress and mother and fetus death in medical methods for cervical dilatation. Therefore, this study was designed.

 

This was a Randomized clinical trialwhich was performed between December 2016 and Septem-ber 2019. Women visiting delivery block in Besat Hospital and had the indication of labor induction were examined. Inclusion criteria in the study were: gestational age equaling or greater than 37 weeks (based on first trimester sonography and certain LMP), unfit cervix (Bishop score 1 equaling or less than 4), single-shot pregnancy, vertex display, intact membrane and patient’s consent to participate in the study. Patients were also homogenized in term of gravid distribution. Criteria for exiting the study were cesarean back-ground, previous uterine surgery, vaginal bleeding, placenta previa, the possibility of placenta abruption, regular uterine contractions, potential susceptibility to contra-indication of prostaglandins and IUGR fetuses and severe preeclampsia, problem in controlling the fetal heart rate and fetal distress. Patients were distributed in random 4-part blocks and the methods were randomly attributed to each.
This study was done on pregnant women who showed pregnancy termination indication for any cause (delivery date, post-term pregnancy, hypertension), using a randomized clinical trial. Based on the formula for determining the sample size of patients who had inclusion criteria, the minimum number of patients in each group was 60, and 120 patients were enrolled in the study. The study was approved by the Ethics Committee of the Faculty of Medicine and the procedure was fully explained to the patients, who, in case of written consent, were included in the study. In the first group (misoprostol group), misoprostol at 25 μg (200mg Samisaz tablets divided by divaider) was placed in the posterior fonix of the vagina and was repeated almost every 6 hours to a maximum of 3 doses (75 μg total).
If the patient did not enter the delivery phase (regular uterine contractions accompanied by progressive changes in the cervix), after 12 hours of induction, oxytocin was used to terminate the pregnancy.
In the second group (Foley catheter), including 60 patients, Foley catheter 16 was injected through the cervix under sterile condition (vaginal rinse with iodine) and then a balloon filled with 30 mL of distilled water, was placed behind the interior hole. Then, the other end of the catheter was attached to the patient's bed to a 500 mL serum to create stretching. If, after 6 hours, the patient did not enter the active phase on her own, labor induction began using oxytocin.
The fetal heart rate and maternal uterine contractions were monitored every 15 minutes. The age of the mother, the gestational age, the initial bishop scores (before the onset of induction), the interval between the start of the procedure and the beginning of the active phase, the interval between the onset of the method and the delivery, active phase duration, the mode of delivery, the baby’s Apgar score in both groups were recorded and compared with each other. Descriptive statistics has been used to summarize and report the results of the effects of Foley catheter and vaginal misoprostol in terms of their variables. In order to compare these two methods, in terms of induction rate and Bishop Score, independent t test was used. To compare the two methods from the point of view induction security, the X² test was used.