Breast Stimulation vs. Low Dose Oxytocin for Labor Augmentation in Women with a Previous Cesarean Delivery, a Randomized Controlled Trial.

Background: Oxytocin and breast stimulation are methods used for labor augmentation in women with a previous cesarean delivery (CD). Compared to spontaneous labor, labor augmentation has been shown to increase the risk of uterine rupture in women with a previous CD. The optimal method of labor augmentation for women with a prior CD has not been established.

Objective: In a cohort of patients with one previous CD, we aimed to compare maternal and neonatal outcomes according to the method of labor augmentation; breast stimulation or intravenous oxytocin.

Study Design: This randomized controlled trial (RCT) was conducted at a single, tertiary, university-affiliated hospital. The participants had one previous CD and a cervical dilatation of 2-6 cm, had inadequate uterine contractions, defined as less than 3 per 10 minutes, and were candidates for labor augmentation. They were randomized for augmentation by breast stimulation using a breast pump, or by intravenous low-dose oxytocin starting at 0.5-2 milliunits/minutes, and increasing incrementally by 1-2 milliunits/minutes every 15-40 minutes.. An intrauterine pressure catheter was inserted. Both augmentation treatments were continued for a maximum of 12 hours. If active labor did not occur within 12 hours, the intervention was deemed a failure. An intention-to-treat analysis was performed. The co-primary outcomes were the time from augmentation to delivery, and uterine contraction intensity as measured by Montevideo units. Secondary outcomes included intervention failure, meconium-stained amniotic fluid, vaginal delivery after cesarean section, uterine rupture, infectious outcomes, postpartum hemorrhage, and maternal hospitalization length. The neonatal outcomes included: Apgar score at 5 minutes, umbilical cord pH<7.1, neonatal intensive care unit admission, asphyxia, and perinatal death.

Results: The breast stimulation and the intravenous oxytocin groups included 33 and 34 patients, respectively. The participants' demographic and obstetric characteristics were similar. The median time from augmentation to delivery was longer in the breast stimulation than the oxytocin group: 10.9 hours (total range 1.5-63.2) vs. 5.1 hours (0.8-30), p<0.001. The median (range) contraction intensity as measured by Montevideo units was similar between the groups in the first stage of labor, 125 (70-270) vs. 180 (80-280), p=0.110; and in the second stage of labor, 145 (30-280), vs. 175 (50-290), p=0.164. The tachysystole rate was lower, with statistical significance, in the breast stimulation than the oxytocin group, 6% vs. 27%, p=0.044; while the rates of tachysystole-associated non-reassuring fetal heart rates did not differ significantly, 6% vs. 21%, p=0.427. . Similar proportions of patients delivered within 24 hours of intervention. Uterine rupture occurred in two patients in the oxytocin group (5.6%) and in none in the breast stimulation group, p=0.492. The delivery route and neonatal outcomes were similar between the groups. .

Conclusion: We showed that among patients with one previous CD, breast stimulation compared to intravenous oxytocin was effective, with similar vaginal delivery rates and deliveries within 24 hours, and less frequent tachysystole. A larger RCT is needed to confirm the safety of augmentation by breast stimulation.