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Epidurals and labour

Review
Results
Comment

A review on the effect of epidural analgesia and the Caesarean section rate featured in Bandolier 34 concluded, from two randomised and four non-randomised studies, that epidurals increased the rate of section. A new review [1], with much more data from larger randomised studies, not only comes to a sensible conclusion that Caesarean section rates are unaffected, compared with parenteral opioids, but also has much useful secondary data on maternal and neonatal outcomes.

Review


The review had a thorough search strategy for randomised studies comparing epidural analgesia with parenteral opioids. It used MEDLINE, the Cochrane Library, and hand searched non-abstracted journals and meeting abstracts. It obtained information from authors of abstracts and papers where needed. The primary outcome measure was the Caesarean section rate. There were many secondary outcomes sought.

Results


Ten studies met the inclusion criteria, with 1614 nulliparous and 755 multiparous patients randomised. All but one study provided information on an intention-to-treat basis. The parenteral opioid was predominantly pethidine (meperidine) given by intramuscular or intravenous injection; one study used intravenous fentanyl and another intravenous butorphanol.

The Caesarean section rate was 8.2% with epidural and 5.6% with parenteral opioid (Figure). They found no significant difference using a random-effects model for odds ratios. The implication is that there may be one additional Caesarean section for every 40 women given an epidural rather than parenteral opioid. Caesarean section rates were no different with epidural or parenteral opioid for nulliparous women (about 8%) or multiparous women (about 2.5%).

Figure: Caesarian section rates with epidural and parenteral opioid analgesia. Each point is one trial (filled circles are trials in original review).


There were a number of secondary outcomes for mothers and babies (Table). For mothers, epidurals resulted in much less pain in the first and second stages of labour, and much less dissatisfaction. However, the cost was a higher rate of instrumental delivery, longer labours, more use of oxytocin and more episodes of hypotension and elevated temperature. For newborns, epidurals resulted in fewer babies with low APGAR scores or low umbilical pH, and fewer needing naloxone.

Maternal outcome Studies/ Patients Result: NNT or NNH (95%CI)

Better outcomes with epidural

First stage labour pain 6/ 2031 Average 40 mm lower with epidural (95%CI 38 to 42 mm) on 100 mm scale
Second stage labour pain 5/ 1062 Average 29 mm lower with epidural (95%CI 21 to 38 mm) on 100 mm scale
Dissatisfaction 5/ 1581 15% with epidural, 43% with parenteral opioid. NNT 3.6 (3.1 to 4.3)

Worse outcomes with epidural  

Instrumental delivery 9/ 2319 15% with epidural, 9% with parenteral opioid. NNH 15 (11 to 26)
First stage labour duration 5/ 1079 Average 42 minutes longer with epidural (95%CI 17-68 minutes)
Second stage labour duration 6/ 1190 Average 14 minutes longer with epidural (95%CI 5-23 minutes)
Use of oxytocin after analgesia 4/ 1001 45% with epidural, 32% with parenteral opioid. NNH 7.9 (5.4 to 15)
Temperature >38 °C 2/ 1371 23% with epidural, 5% with parenteral opioid. NNH 5.6 (4.7 to 7.0)
Hypotension 3/ 1684 37% with epidural, 0% with parenteral opioid. NNH 2.7 (2.5 to 3.0)

No difference between epidural and parenteral opioid  

Nausea 5/ 835 7% with epidural, 6% with parenteral opioid. No significant difference
Instrumental delivery for dystocia 2/ 211 12% with epidural, 17% with parenteral opioid. No significant difference
Neonatal outcome Studies/ Patients Result: NNT (95%CI)

Better outcomes with epidural  

APGAR <7 at 1 minute 6/ 2015 1% with epidural, 2% with parenteral opioid. NNT 68 (40 to 231)
APGAR <7 at 5 minutes 7/ 2176 4% with epidural, 7% with parenteral opioid. NNT 35 (21 to 112)
Low umbilical artery pH 6/ 2034 14% with epidural, 17% with parenteral opioid. NNT 27 (15 to 220)
Need for naloxone in the newborn 2/ 815 1% with epidural, 3% with parenteral opioid. NNT 37 (22 to135)

No difference between epidural and parenteral opioid  

Foetal heart rate abnormal, or intrapartum meconium 3/ 1126 19% with epidural, 20% with parenteral opioid. No significant difference
Severe asphyxia (umbilical artery pH <6.99) 5/ 1715 <1% on both. No significant difference

Comment


The bulk of the information in this review was published after that featured in Bandolier 34 (and published in 1994) was completed. There is now information on over 10 times as many randomised patients than in the earlier review. It shows clearly that the earlier trials over-estimated any increased Caesarean section rate with epidural analgesia in labour.

Reference:

  1. SH Helpern et al. Effect of epidural vs parenteral opioid analgesia on the progress of labour. JAMA 1998 280: 2105-10.
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