LAS VEGAS –
dimarik/iStock/Getty Images
In a randomized, controlled trial of 346 nulliparous women, the device, adapted from a design used in athletics, made no difference in the duration of the second stage of labor overall or in passive descent or active pushing time. The findings were presented on behalf of first author Eric Bergh, MD, by Patricia Rekawek, MD, at a fellows abstract session at the meeting sponsored by the Society for Maternal-Fetal Medicine. Dr. Rekawek and Dr. Bergh are maternal-fetal medicine fellows at the Icahn School of Medicine at Mount Sinai, New York.
The dental support device (DSD) was actually used by 128 (74%) of the patients who were randomized to DSD usage. Of these patients, two thirds (n = 85) used the device for all second stage contractions. About one quarter (27%; n = 35) used it less than half the time, and a small minority (6%; n = 8) used it more than half the time but not for all pushing, noted Dr. Rekawek.
Most women (61%) who used the device agreed or strongly agreed that it was helpful. Most also found it comfortable (67%), and would use it again in a future delivery (61%). Having a custom-fit DSD, or spending more time practicing before labor, might help with efficacy in shortening the second stage of labor and merits study, the investigators said.
Reducing time spent in the second stage of labor could benefit both mother and neonate because “a prolonged second stage of labor is associated with multiple maternal and neonatal complications,” including increased risk for chorioamnionitis, neonatal sepsis, low umbilical artery pH, shoulder dystocia, and third- and fourth-degree lacerations, said Dr. Rekawek.
In athletics, a DSD “raises the vertical dimension of the deep bite and increases the size of the oropharynx” by introducing a 3-mm bite plate between the upper and lower rear molars. The DSD mouthpiece integrates the bite plates with a retainer-like band that wraps around the front incisors; speaking and drinking are possible with the DSD in place, said Dr. Rekawek.
She added that athletic evidence suggests that the DSD can lead to increased oxygenation, less head and neck tension, less muscle fatigue, and improved exercise capacity in some sports.
If these benefits translated to the maternal Valsalva maneuver during the second stage of labor, the increased isometric endurance could increase uterine pressure and optimize the expulsive effect of pushing, explained Dr. Rekawek. However, mixed results were seen in previous work that had women using a DSD during the second stage of labor.
The current study was powered to detect a difference of 20% in the duration of the second stage of labor for nulliparous women who were randomized either to use or not use a DSD while pushing. Women and their caregivers learned their random allocation by opening a sealed envelope at the beginning of the second stage of labor.
The study included nulliparous women who were carrying a singleton pregnancy of at least 37 weeks’ gestation and without known fetal anomalies. Enrollment occurred before the second stage of labor, and 173 women participated in each arm of the study.
For those who were assigned to use the DSD, the second stage of labor lasted a median 84 minutes, whereas the median for the control group was 92 minutes (P = .11) in an intention-to-treat analysis. Passive descent and active pushing lasted a median 14 and 50 minutes, respectively, for the DSD group, compared with 13 and 55 minutes for the control group (P = .22 and P = .29, respectively).
Another analysis of the primary outcome measure used Kaplan-Meier curves to compare the curves of the women who remained pregnant in each group across the period of the second stage of labor. There was no significant difference between the groups when the data were examined in this manner (log rank P = .18).
Secondary maternal outcomes included the mode of delivery. Most women (83%-85%) in each group had a normal spontaneous vaginal delivery, with no differences in any mode of delivery (P = .93). Neonatal outcomes also were similar between groups, with no significant differences in sex, birth weight, arterial pH, and neonatal intensive care unit admissions.
The investigators tracked whether patients were admitted in spontaneous labor, for labor induction with active membranes, or with premature rupture of membranes. Also, they looked at the degree of cervical dilation at admission, whether oxytocin or epidural anesthesia were used in labor, and anesthetic administered during the second stage of labor. There were no differences between groups in these variables.
Dr. Rekawek noted that the study benefited from a large sample size and a prospective, randomized design. Blinding lasted only until pushing began. Also, although all patients were taught how to use the device, they didn’t have an opportunity to practice.
Dr. Rekawek presented on behalf of Dr. Bergh because he became a new father the day before the presentation. His wife, said Dr. Rekawek, didn’t use a dental support device.
The authors reported that they have no relevant financial disclosures.
SOURCE: Bergh E et al. Am J Obstet Gynecol. 2019 Jan;220(1):S39, Abstract 49.