The nature of labor pain

Background
For centuries, there has been controversy around whether being upright (sitting, birthing stools, chairs, squatting, kneeling) or lying down (lateral (Sim's) position, semi-recumbent, lithotomy position, Trendelenburg's position) have advantages for women giving birth to their babies. This is an update of a review previously published in 2012, 2004 and 1999.

Objectives
To determine the possible benefits and risks of the use of different birth positions during the second stage of labour without epidural anaesthesia, on maternal, fetal, neonatal and caregiver outcomes.

Search methods
We searched Cochrane Pregnancy and Childbirth's Trials Register (30 November 2016) and reference lists of retrieved studies.

Selection criteria
Randomised, quasi-randomised or cluster-randomised controlled trials of any upright position assumed by pregnant women during the second stage of labour compared with supine or lithotomy positions. Secondary comparisons include comparison of different upright positions and the supine position. Trials in abstract form were included.

Data collection and analysis
Two review authors independently assessed trials for inclusion and assessed trial quality. At least two review authors extracted the data. Data were checked for accuracy. The quality of the evidence was assessed using the GRADE approach.

Main results
Results should be interpreted with caution because risk of bias of the included trials was variable. We included eleven new trials for this update; there are now 32 included studies, and one trial is ongoing. Thirty trials involving 9015 women contributed to the analysis. Comparisons include any upright position, birth or squat stool, birth cushion, and birth chair versus supine positions.

In all women studied (primigravid and multigravid), when compared with supine positions, the upright position was associated with a reduction in duration of second stage in the upright group (MD -6.16 minutes, 95% CI -9.74 to -2.59 minutes; 19 trials; 5811 women; P = 0.0007; random-effects; I² = 91%; very low-quality evidence); however, this result should be interpreted with caution due to large differences in size and direction of effect in individual studies. Upright positions were also associated with no clear difference in the rates of caesarean section (RR 1.22, 95% CI 0.81 to 1.81; 16 trials; 5439 women; low-quality evidence), a reduction in assisted deliveries (RR 0.75, 95% CI 0.66 to 0.86; 21 trials; 6481 women; moderate-quality evidence), a reduction in episiotomies (average RR 0.75, 95% CI 0.61 to 0.92; 17 trials; 6148 women; random-effects; I² = 88%), a possible increase in second degree perineal tears (RR 1.20, 95% CI 1.00 to 1.44; 18 trials; 6715 women; I² = 43%; low-quality evidence), no clear difference in the number of third or fourth degree perineal tears (RR 0.72, 95% CI 0.32 to 1.65; 6 trials; 1840 women; very low-quality evidence), increased estimated blood loss greater than 500 mL (RR 1.48, 95% CI 1.10 to 1.98; 15 trials; 5615 women; I² = 33%; moderate-quality evidence), fewer abnormal fetal heart rate patterns (RR 0.46, 95% CI 0.22 to 0.93; 2 trials; 617 women), no clear difference in the number of babies admitted to neonatal intensive care (RR 0.79, 95% CI 0.51 to 1.21; 4 trials; 2565 infants; low-quality evidence). On sensitivity analysis excluding trials with high risk of bias, these findings were unchanged except that there was no longer a clear difference in duration of second stage of labour (MD -4.34, 95% CI -9.00 to 0.32; 21 trials; 2499 women; I² = 85%).

The main reasons for downgrading of GRADE assessment was that several studies had design limitations (inadequate randomisation and allocation concealment) with high heterogeneity and wide CIs.

Authors' conclusions
The findings of this review suggest several possible benefits for upright posture in women without epidural anaesthesia, such as a very small reduction in the duration of second stage of labour (mainly from the primigravid group), reduction in episiotomy rates and assisted deliveries. However, there is an increased risk blood loss greater than 500 mL and there may be an increased risk of second degree tears, though we cannot be certain of this. In view of the variable risk of bias of the trials reviewed, further trials using well-designed protocols are needed to ascertain the true benefits and risks of various birth positions.

/pdf/position-in-the-second-stage-of-labour-for-women-without-40ely3hhxh.pdf

Position in the second stage of labour for women without epidural anaesthesia

The effectiveness of two epidural analgesic regimens on the ability to ambulate was compared in women in labor by a prospective, randomized, double-blind design. One group of patients received epidural fentanyl, a 75-micrograms bolus and an infusion of fentanyl 2.5 micrograms/mL at 15 mL/h (FENT, n = 53). A second group received ultra low-dose bupivacaine (0.04%), epinephrine (1.7 micrograms/mL), and fentanyl (1.7 micrograms/mL) (BEF, n = 77), a 15-mL bolus followed by an infusion at 15 mL/h. Adequate analgesia was rapidly obtained in 90.6% of patients in the FENT group and 92.2% of patients in the BEF group (P = 0.89). Seventy percent of patients in the FENT group ambulated versus 68% in the other group. The BEF mixture provided analgesia of longer duration (287 +/- 171 min versus 156 +/- 72 min, P = 0.0001). The number of patients delivering during administration of only their study drug (without needing higher doses of local anesthetics) was 52% for BEF and 21% for FENT (P = 0.0005). Hip flexion weakness precluding ambulation occurred in 17% (P = 0.002) of BEF patients and orthostatic hypotension in 9% (P = 0.08). Neither problem occurred in FENT patients. Neonatal outcome was similar in both groups. Approximately 70% of women receiving epidural analgesia with fentanyl or ultra low-dose bupivacaine, epinephrine, and fentanyl may ambulate safely during labor.

Epidural anesthesia for labor in an ambulatory patient

Nonpharmacologic relief of pain during labor: systematic reviews of five methods.

Background Among nulliparous women, there appears to be an association between the use of epidural analgesia during labor and an increased risk of dystocia. We tested the hypothesis that combined spinal–epidural analgesia, which permits ambulation during labor, is associated with a lower incidence of dystocia than continuous lumbar epidural analgesia. Methods Between July 1995 and September 1996, we randomly assigned 761 nulliparous women in spontaneous labor at term who requested epidural analgesia to receive either continuous lumbar epidural analgesia or a combination of spinal and epidural analgesia. Among the women who received combined spinal–epidural analgesia, some were discouraged from walking and others were encouraged to walk. Maternal and neonatal outcomes, the incidence of dystocia necessitating cesarean section, and measures of patients' satisfaction were compared in the two groups. Results There were no significant differences in the overall rate of cesarean section, the incidence of dystoci...

https://www.nejm.org/doi/pdf/10.1056/NEJM199712113372402

Epidural Analgesia Compared with Combined Spinal–Epidural Analgesia during Labor in Nulliparous Women

The aim of this paper has been to compare the uterine contractility, pain produced by contractions and comfort of the patients between standing and supine position. The study has been performed in twenty normal nulliparae who were changed from supine to standing position and viceversa at intervals of approximately thirty minutes. Intrauterine pressure and fetal heart rate were continuously monitored. Cervial dilatation was evaluated every thirty minutes. No medication was given to the patients. They were asked to assess the pain produced by uterine contractions in each one of both positions and which was the more comfortable. It has been found: 1. That the intensity of contractions was significantly higher in fifteen out of the twenty patients in standing position. 2. Frequency of contractions diminished significantly in one third of the patients. 3. Uterine activity increased significantly in half of them. 4. Consistently, less pain accompanied uterine contractions in standing position. 5. Patients reported more comfort in this position. The average duration of labor was 3 hrs 55 min. This duration is short, compared with standard clinical experience and with published data. No complications occurred, by the use of standing position during labor, on the mother or fetus. The physiological mechanisms responsible for the above mentioned effects of standing position are unknown. It is condluced that there are no clear arguments against the use of standing position during labor and that this position should be used more frequently in clinical obstetrics, provided obstetrical conditions are similar to those reported in this paper.

/pdf/effects-of-standing-position-on-spontaneous-uterine-2jfjjebw7c.pdf

I. Villa Elízaga

Papers

Effects of standing position on spontaneous uterine contractility and other aspects of labor.