The main purpose of the IOL is to ensure timely cervical ripening and successful vaginal birth. In our study, it was found that 79.4% of term pregnancies treated with dinoprostone slow-release vaginal insert for IOL had a successful vaginal delivery rate. This success rate was consistent with many other previous studies with a successful vaginal delivery rate ranging from approximately 70–90% after using a dinoprostone slow-release vaginal insert for the IOL (29–34). In the 2008 report of the Turkey Demographic and Health Survey (TDHS), the C/S rate was found to be 37%, and in the TDHS-2013 report, it was 48% (35–37). These rates are significantly higher than the 15% rate given as an acceptable cesarean delivery rate by the World Health Organization (38). In light of this information, the successful birth rate data in our study reveal that dinoprostone administration is an effective method for successful initiation of labor. In our study, we demonstrated that parity is one of the most important determinants in achieving successful vaginal delivery in term pregnancies treated with dinoprostone slow-release vaginal insert for IOL. 96.7% of all multiparous women had a successful vaginal delivery, and in the nulliparous group, the rate of successful vaginal delivery after dinoprostone slow-release vaginal insert treatment was determined as 70.2%. However, there are different results in the literature regarding the successful delivery rates of dinoprostone application in multiparous and nulliparous pregnant women (39, 40).In a retrospective study by Zhao et al., results revealed that parity was the strongest and most significant predictor of successful vaginal delivery in term pregnancies when comparing the efficacy of dinoprostone slow-release vaginal insert between multiparous and nulliparous women (41). In the study by Huang et al., parity was proven to be the main factor contributing to the time to vaginal delivery, and a significant decrease in the time to vaginal delivery was observed in multiparous women compared to nulliparous women (42). In present study, the mean age was found to be significantly higher in the unsuccessful vaginal delivery group. In the study conducted by Pevzner et al., it was revealed that a maternal age of < 35 years significantly supports successful labor induction (43). Similarly, in the study conducted by Obut et al., it was revealed that increasing maternal age reduces the probability of vaginal delivery (44). In present study, no statistically significant relationship was found between gestational age, birth weight, IOL indication and use of painless anesthesia parameters and successful vaginal delivery. Possible reasons could be the small sample size, because if the sample size is limited, other less important factors cannot reach the level of statistical significance. Only the most significant and important factor can be repeated in almost all studies. In the literature, labor induction is shown to be more likely to be successful in women with lower BMI (45, 46). In our study, similar to the literature, BMI was found to be significantly lower in pregnant women who had successful vaginal births. Higher bishop scores have traditionally been associated with higher vaginal birth success rates (47, 48). However, there are studies that question the reliability of bishop scores in predicting final birth outcome (49, 50). In our study, bishop scores were found to be significantly higher in patients who had a successful vaginal delivery with vaginal dinoprostone administration, based on the results obtained in most randomized trials and clinical guidelines for labor induction (51, 52). In our study, the 1st and 5th minute Apgar scores of patients who had a successful vaginal delivery were found to be significantly higher. In the literature, neonatal outcomes were found to be positive in pregnancies induced with dinoprostone (41, 53). In our study, time to delivery after insertion (hours) and time to delivery after retrieval (hours) were found to be significantly lower in patients who had a successful vaginal delivery compared to patients who could not have a vaginal delivery. Similarly, in the literature, the time to delivery after insertion (hours) and time to delivery after retrieval (hours) were found to be lower in patients who had a successful delivery with dinoprostone compared to patients who underwent spontaneous delivery follow-up or underwent C/S due to induction failure. Whether epidural analgesia increases the risk of cesarean delivery and prolongs labor has been intensely debated during the last decade (54). Unfortunately, good studies are few and most have had small numbers of subjects. In the study conducted by Hasegawa et al., it was stated that epidural analgesia was associated with slow progress of labor, which increased the rate of instrumental delivery. However, in our study, no relationship was found between the use of painless anesthesia and the success of vaginal delivery. In our study, uterocervical angle measurement was found to be significantly higher in patients who had successful vaginal delivery compared to patients who could not have vaginal delivery. However, in the study conducted by İleri et al., no relationship was found between uterocervical angle and delivery success in pregnancies induced with dinoprostone (55). In the study conducted by Yang et al., it was stated that the use of uterocervical angle measurement and bishop score together could help predict the success of labor induction (56). In another study in the literature, it was stated that uterocervical angle could be used in addition to cervical length measurement in the risk of premature birth and term pregnancy in predicting delivery success (57). Our study showed that the success rate of vaginal delivery in nulliparous term pregnancies was only 70.2%, suggesting that other strategies may be considered instead of the dinoprostone slow-release vaginal insert for IOL in nulliparous term pregnancies. In fact, many studies have supported the use of PGE1, and some have suggested the combination of mechanical methods and pharmacological methods or the use of mechanical or pharmacological agents alone, compared with PGE2 (58). A randomized controlled trial by Edwards et al. compared the combined use of a dinoprostone slow-release vaginal insert and a foley catheter with the use of a foley catheter alone for cervical ripening and labor induction. This study supported the combined use of a dinoprostone slow-release vaginal insert and a foley catheter for cervical ripening over the use of a foley catheter alone for IOL in nulliparous term pregnant women. The results showed that the combination strategy could shorten the time to vaginal delivery in nulliparous women but not in multiparous women (59).