Trial design

The EVADELA (Evaluation of Decubitus Lateral Asymmetric posture) trial was an open multicenter randomized controlled trial with 2 parallel groups, conducted in 4 French maternity units from May 2013 through December 2014.

Before the trial began, all participating midwives and obstetricians in each maternity unit received instruction in the protocol procedures and reviewed the LAD posture to ensure its consistency for all clinicians. One midwife was identified as the local study investigator in each center.

Participants

Participants were recruited in 2 tertiary university maternity units (in Port-Royal, Paris: 5500 deliveries/year; in the Woman and Child Department of Caen Hospital, Normandy: 3000 deliveries/year), a level-2 maternity unit (Avranches-Granville, Normandy: 1300 deliveries/year), and a level-1 unit (Les Bluets, Paris; 3000 deliveries/year).

Eligible women were ≥18 years old, in labor with ruptured membranes, and with a singleton term fetus (≥37 weeks of gestation) in an OP position clinically diagnosed between 2 and 9 cm of cervical dilation and confirmed by transabdominal ultrasound imaging just above the symphysis, demonstrating the position of the fetal orbits, the falx, and the fetal spine. We excluded women with complications during pregnancy, small-for-gestational age fetuses, in utero fetal deaths, and those who did not understand French. We also excluded women who were using the LAD posture before inclusion and randomization.

Women first received information about the study during a prenatal visit in the third trimester of pregnancy from clinicians (midwives or obstetricians). Fliers about the study were also posted in each maternity unit. This information was repeated in the delivery room for women in labor when the clinician determined that the fetus was in an OP position. When this diagnosis was confirmed by the ultrasound examination (paper printouts of the ultrasound examinations were provided), women were asked to confirm their participation and provide written consent. After inclusion, they were assigned randomly to the intervention or the control group.

Intervention

In the intervention group, women were postured in the LAD posture for the first hour after randomization (a minimum of 30 minutes required; Figure 1 ). LAD was a pronounced lateral recumbent posture, lying on the side opposite that of the fetal spine (eg, right maternal lateral position for left fetal spine) with the inferior leg positioned in the axis of the body and the upper leg hyperflexed (spine-femur angle, <90 degrees) with the shin propped up on a stirrup. Because maternal posture should be maintained for a significant length of time to be efficient, we chose a 1-hour posture. After the first hour after randomization, women were encouraged to maintain this posture as long as possible during the first stage of labor.

In the control group, women used the dorsal recumbent posture for the first hour after randomization and were then encouraged to maintain it for as long as possible during labor. If women wanted to change their posture later in labor or if they needed to because of fetal heart rate (FHR) abnormalities, they could take any position except LAD.

In both groups, once dilation was complete, midwives and obstetricians could recommend other maternal postures or attempt manual rotation, according to the unit’s regular practices.

Each participating clinician received a didactic protocol with a description of each stage of the study and an illustration of the LAD posture; the protocol was also posted in the labor ward.

Outcomes

The primary outcome was the rate of OA position of the fetal head 1 hour after randomization, clinically diagnosed and confirmed by ultrasound imaging (paper printouts of ultrasound examinations provided). The fetal head position was classified into 1 of 3 categories: OA position (including right and left OA positions), occiput transverse position (right and left), and OP position (including right or left OP positions). For women who gave birth before the end of the first hour after randomization, we considered the fetal head position at birth as the fetal head position for this outcome.

The main secondary outcomes were the frequency of the OA position at complete cervical dilation (confirmed by an ultrasound examination) and at delivery. Manual fetal head rotations that were performed at complete cervical dilation were recorded. For women who gave birth before complete dilation, we considered the fetal head position at complete dilation to be missing.

Maternal secondary outcomes were speed of cervical dilation during labor (centimeters/hour), length of expulsive efforts (minutes), mode of delivery (spontaneous, instrumental, or cesarean), perineal lacerations in vaginal deliveries (episiotomy or third- and fourth-degree lacerations), hyperthermia (temperature, ≥38°C), postpartum hemorrhage (blood loss, ≥500 mL), and severe postpartum hemorrhage (defined as a blood loss >1000 mL or the need for a supplementary uterotonic treatment, uterine balloon tamponade, arterial embolization, uterine artery ligation, or hysterectomy).

Neonatal outcomes included umbilical arterial pH at birth, 5- and 10-minute Apgar scores, neonatal resuscitation (ventilation or intubation), and transfer to neonatal intensive care unit. Moreover, gestational age at birth, sex, weight, height, and head circumference of neonates were also recorded.

Safety outcomes included the rate of FHR assessments that were considered to be of poor quality (satisfactory/acceptable/unsatisfactory) and the frequency of FHR signal loss (<10%, 10-25%, 25-50%, >50%) during the first hour after randomization. In this study, as in France in general, FHR was monitored continuously throughout labor. Finally, women’s satisfaction was assessed with questions about the comfort of the posture (very comfortable/comfortable/not really comfortable/uncomfortable) and pain intensity at 1 hour after randomization (using the Visual Analogue Scale).

To assess the comparability of the 2 groups, the following maternal characteristics were compared: age, parity (primiparous/multiparous), gestational age at birth, prepregnancy body mass index, geographic origin, and educational level. Other factors that might have an effect on the fetal head position or its rotation were also collected: cervical dilation at randomization, placental location, fetal head station, induction of labor (spontaneous/induced), oxytocin use, and epidural.

Midwives and obstetricians random assigned the women and conducted the vaginal and ultrasound examinations at inclusion, at the end of the first hour after randomization, and at complete cervical dilation. They also prospectively collected fetal head position at birth and details about the postures that were used by each woman (number and description of each) and about manual rotation and FHR signal loss. A research assistant independent of the local medical team collected other data from the medical charts: compliance with the inclusion criteria and the randomization procedure. Another independent research assistant who was used only for the data monitoring checked the quality of data for all participants.

Sample size

We estimated the number of patients necessary based on OA position rates at the end of the 1-hour study period close to those reported by Stremler et al. Thus, we hypothesized that the rate of OA fetal head positions 1 hour after randomization would be 15% in the intervention group vs 5% in the control group. To show this difference with a bilateral test, a power of 80% (1-β), and an alpha risk of .05, the study required the inclusion of 160 women in each group, for a total of 320 participants with a 1:1 ratio.

Randomization

As soon as the written consent was signed, the randomization was performed by an automated web-based system to ensure allocation concealment (24-hour accessibility with personal login and password: Cleanweb software; Telemedicine Technologies S.A, Boulogne-Billancourt, France). Allocation was based on permutated blocks of 4 and was stratified by center and parity (primiparous/multiparous). This strategy was not known by local investigators.

Statistical methods

The data analysis was conducted, and the manuscript written in accordance with the Consolidated Standards of Reporting Trials guidelines. The 2 groups were compared for the main and secondary outcomes in an intention-to-treat analysis. For dichotomous variables, proportions were calculated, and chi and Fisher exact tests were used as appropriate to assess differences in outcomes between groups. For continuous variables, we calculated means and their standard deviations and used Student and nonparametric tests to compare the outcomes between groups. Rates of episiotomy or perineal lacerations and the mean duration of expulsive efforts were calculated only among women with vaginal deliveries. The speed of cervical dilation was defined as mean cervical dilation measured in centimeters per hour of labor and calculated with the following formula: (10–cervical dilation at inclusion)/(time at complete dilation–time at inclusion) for both the subgroups of women with vaginal and cesarean deliveries. We stratified the primary and secondary fetal position outcomes according to the fetal position category at inclusion (right or left OP or OP), cervical dilation at inclusion, and the actual duration for which the women in the intervention group maintained the LAD position for the first hour.

The effect of the LAD position was assessed globally and for each center. A Mantel-Haenszel homogeneity test was performed to assess the consistency of the main outcome across all the 4 centers and according to parity. Significance was defined as a probability value of <.05. Analyses were performed with Stata software (version 10SE; Stata Corporation, College Station, TX).

Ethics and registration

The Ile-de-France XI Committee for the Protection of Persons (Ethics committee) approved the trial protocol in February 2013 (n°13011). It has been registered in the Clinical Trials database ( ClinicalTrials.gov ): number: NCT01854450 .