Comparison of Low-Dose Oxytocin and Dinoprostone for Labor Induction in Postterm Pregnancies: A Randomized Controlled Prospective Study

Abstract

Aims: The aim of this study was to compare the efficacy of oxytocin and dinoprostone in achieving successful labor induction and vaginal delivery in postterm women with an unfavorable cervix. Methods: Postterm women with an uncomplicated pregnancy and a Bishop score of ≤6 were randomized to receive either dinoprostone vaginal pessary (Propess®) or low-dose oxytocin. The primary outcomes were the length of the induction-to-delivery period and the incidence of vaginal delivery. Results: A total of 144 women were available for the analysis. The overall vaginal delivery rates were 75% (54/72) for the dinoprostone group and 80.6% (58/72; p = 0.35) for the oxytocin group; the mean induction-to-vaginal delivery interval was 13.3 and 10.3 h in the dinoprostone and the oxytocin group, respectively (p = 0.003). Uterine hyperstimulation was 7.4% compared with 6.8% (p = 0.8), and abnormal fetal heart rate was 26.4% compared with 18% (p = 0.2), respectively. Conclusion: Both oxytocin and dinoprostone seem to have similar obstetric outcomes in postterm pregnancies with an unfavorable cervix, except for a significant superiority of oxytocin for delivery in a shorter period.

Risk Factors for Cesarean Delivery after Induction of Labor in Nulliparous Women with an Unfavorable Cervix at or beyond 41 Weeks of Gestation

“…Unfavorable cervix defined as a Bishop score ≤6. Cervical ripening was performed with intracervical prostaglandin E 2 gel or oxytocin [25]. Induction of labor with oxytocin infusion begun at 4 mU/min and increased by 4 mU/min every 20 min to a maximum of 40 mU/min.…”

Effects of intravaginally inserted controlled-release dinoprostone and oxytocin for labor induction on umbilical cord blood gas parameters

“…Arterial and venous umbilical cord gas parameters have been found to be unaffected by oxytocin augmentation or induction (11,13). Moreover Apgar scores, which indicate the well being of newborn infants, were shown to be statistically similar in women induced with dinoprostone and oxytocin (5,12). We found that all Apgar scores were ≥7, all umbilical artery pHs were above 7.10, and none of the newborns experienced fetal acidosis.…”

“…Uterine perfusion decreases during contractions, and increased uterine activity has negative effects on uteroplacental and fetoplacental circulation (11). Intravenous oxcytocin was shown to result in hyperstimulation in 8.3-11.1% of women and fetal distress in 15.9-18%, suggesting that oxytocin application during labor may trigger fetal oxidative stress (5,12). However, oxytocin did not have any negative effects on pH and did not increase perinatal risk (11,13).…”

“…Thus, the use of oxytocin to assist labor does not have negative effects on the fetus (11,13). Intracervical or intravaginal application of dinoprostone (PGE 2 ) is also frequently used to induce labor (5,6,10). Long term treatment with low-dose controlled dinoprostone was well tolerated by both the mother and the fetus (14), with uterine hyperstimulation rates of 7.4-7.8% and fetal distress rates of 10.9-26% (5,12).…”

“…Intracervical or intravaginal application of dinoprostone (PGE 2 ) is also frequently used to induce labor (5,6,10). Long term treatment with low-dose controlled dinoprostone was well tolerated by both the mother and the fetus (14), with uterine hyperstimulation rates of 7.4-7.8% and fetal distress rates of 10.9-26% (5,12). In comparison, we observed lower uterine hyperstimulation (2.6%) and fetal distress (7.7%) rates in our dinoprostone group, whereas the fetal distress rate in our oxytocin group was 9.3%.…”