Epidural bupivacaine concentration and forceps delivery in primiparae

A prospective randomised trial on the effect of position in the passive second stage of labour on birth outcome in nulliparous women using epidural analgesia

OBJECTIVE

To determine whether the rate of instrumental birth in nulliparous women using epidural analgesia is affected by maternal position in the passive second stage of labour.

DESIGN

A pragmatic prospective randomised trial.

SETTING

Consultant maternity unit in the Midlands.

PARTICIPANTS

One hundred and seven nulliparous women using epidural analgesia and reaching the second stage of labour with no contraindications to spontaneous birth.

INTERVENTIONS

The lateral versus the supported sitting position during the passive second stage of labour.

MEASUREMENTS

Mode of birth, incidence of episiotomy, and perineal suturing.

FINDINGS

Recruitment was lower than anticipated (107 vs. 220 planned). Lateral position was associated with lower rates of instrumental birth rate (lateral group 33%; sitting group 52%; p=0.05, RR 0.64, CI for RR: 0.40-1.01; Number-needed-to-treat (NNT)=5), of episiotomy (45% vs. 64%; p=0.05, RR 0.66, CI for RR: 0.44-1.00, NNT=5), and of perineal suturing (78% vs. 86%; p=0.243, RR 0.75, CI for RR 0.47-1.17). The odds ratio for instrumental birth in the sitting group was 2.2 (CI 1.00-4.6). Logistic regression of potential confounder variables was undertaken, due to a large variation in maternal weight between the randomised groups. Of the nine possible confounders tested, only position of the baby's head at full dilation affected the risk of instrumental birth significantly (p=0.4, OR 2.7 where the fetal head was in the lateral or posterior position). Maternal weight did not appear to have any effect. The odds ratio for instrumental delivery for women randomised to the sitting position was slightly higher within the logistic regression model (adjusted OR 2.3).

KEY CONCLUSIONS

Women randomised to the lateral position had a better chance of a spontaneous vaginal birth than those randomised to the supported sitting position. Position of the babies head at full dilation had an additional effect on mode of birth. These effects are not conclusively generalizable. RECOMMENDATIONS FOR PRACTICE: The lateral position is likely to be at best beneficial, and at the worst no less harmful than the sitting position for most women and their babies who meet the criteria set for this study. Conclusive evidence for or against the technique should be established using larger trials.

Does epidural analgesia influence the mode of delivery in primiparae managed actively? A preliminary study of 1250 women

We studied 1250 primiparous women with a singleton pregnancy, gestational age at delivery of 37-42 weeks, with a single live fetus, vertex presentation whose first and second stages of labour were managed according to strict criteria for the active management of labour. 568 (45%) received epidural analgesia (bupivacaine 0.25%) during labour, and the other 682 (55%) received either Entonox, pethidine or no analgesia. The spontaneous vaginal delivery rate in the epidural group was 67% (95% confidence interval [CI] 63-71%), lower than that in the non-epidural group (87%, 95% CI 84-90%). All instrumental delivery rates were higher in the epidural group. However, the rotational forceps rate in the epidural group (2.5%, 95% CI 1.4-4.1%) was only marginally higher than in the non-epidural group (0.9%, 95% CI 0.3-1.9%). Women who were induced were more likely to request an epidural (56%: 95% CI 50-61%) than those with spontaneous onset of labour (41%: 95% CI 38-45%). Whether labour was spontaneous or induced, a higher proportion of women who received epidural required oxytocin augmentation. The effects of combinations of epidural analgesia, the need for oxytocin augmentation and induction of labour on mode of delivery were additive. This preliminary study suggests that a high rate of spontaneous vaginal delivery can be achieved with epidural analgesia when labour is actively managed.