Early versus late initiation of epidural analgesia for labour

Epidural analgesia involves the injection of medication just outside the spinal column. It is an effective form of pain relief during labour. The intensity of the pain increases as labour progresses. Epidural analgesia is an invasive procedure with side effects and more rarely complications. Reported side effects include muscle weakness, nausea, shivering, itching and headache. Epidural analgesia with low concentration infusions of bupivacaine has been shown to not increase the incidence of caesarean section but may increase the incidence of instrumental vaginal delivery and the duration of second stage of labour (Sia 2004). This Cochrane systematic review summarised the best available evidence (published before 12 February 2014) regarding the effectiveness and safety of early initiation versus late initiation of epidural analgesia for both spontaneous and augmented labour. Our meta-analysis involved nine randomised controlled studies with a total of 15,752 women giving birth to their first baby and found no differences in the risk of caesarean section and instrumental birth with early initiation versus late initiation of epidural analgesia for pain relief during labour. Although the effects of early or late initiation of epidural analgesia on the duration of the second stage of labour are similar, we are unable to rule out early initiation leading to an appreciably shorter duration of labour. There was a lot of variation (heterogeneity) between the results of the studies for the duration of the first stage of labour. For the baby, Apgar scores and cord pH were not different. We conclude that it would appear to be advantageous to initiate epidural analgesia for labour early, when requested by the woman.

The studies varied in the definition of early initiation and late initiation of epidural analgesia. Early initiation is typically defined as with cervical dilatation of less than 4 cm to 5 cm, and late initiation with cervical dilatation of 4 cm to 5 cm or more. The dose, concentration and technique of epidural analgesia also varied between the studies. The groups randomised to receive late initiation of epidural analgesia differed in the analgesia they received before the epidural analgesia.

Authors' conclusions: 

There is predominantly high-quality evidence that early or late initiation of epidural analgesia for labour have similar effects on all measured outcomes. However, various forms of alternative pain relief were given to women who were allocated to delayed epidurals to cover that period of delay, so that is it hard to assess the outcomes clearly. We conclude that for first time mothers in labour who request epidurals for pain relief, it would appear that the time to initiate epidural analgesia is dependent upon women’s requests.

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Background: 

Pain during childbirth is arguably the most severe pain some women may experience in their lifetime. Epidural analgesia is an effective form of pain relief during labour. Many women have concerns regarding its safety. Furthermore, epidural services and anaesthetic support may not be available consistently across all centres. Observational data suggest that early initiation of epidural may be associated with an increased risk of caesarean section, but the same findings were not seen in recent randomised controlled trials. More recent guidelines suggest that in the absence of a medical contraindication, maternal request is a sufficient medical indication for pain relief during labour. The choice of analgesic technique, agent, and dosage is based on many factors, including patient preference, medical status, and contraindications. There is no systematically reviewed evidence on the maternal and foetal outcomes and safety of this practice.

Objectives: 

This systematic review aimed to summarise the effectiveness and safety of early initiation versus late initiation of epidural analgesia in women. We considered the obstetric and fetal outcomes relevant to women and side effects of the treatments, including risk of caesarean section, instrumental birth and time to birth.

Search strategy: 

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (12 February 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2014, Issue 1), MEDLINE (January 1966 to February 2014), Embase (January 1980 to February 2014) and reference lists of retrieved studies.

Selection criteria: 

We included all randomised controlled trials involving women undergoing epidural labour analgesia that compared early initiation versus late initiation of epidural labour analgesia.

Data collection and analysis: 

Two review authors independently assessed trials for inclusion, extracted the data and assessed the trial quality. Data were checked for accuracy.

Main results: 

We included nine studies with a total of 15,752 women.The overall risk of bias of the studies was low, with the exception of performance bias (blinding of participants and personnel).

The nine studies showed no clinically meaningful difference in risk of caesarean section with early initiation versus late initiation of epidural analgesia for labour (risk ratio (RR) 1.02; 95% confidence interval (CI) 0.96 to 1.08, nine studies, 15,499 women, high quality evidence). There was no clinically meaningful difference in risk of instrumental birth with early initiation versus late initiation of epidural analgesia for labour (RR 0.93; 95% CI 0.86 to 1.01, eight studies, 15,379 women, high quality evidence). The duration of second stage of labour showed no clinically meaningful difference between early initiation and late initiation of epidural analgesia (mean difference (MD) -3.22 minutes; 95% CI -6.71 to 0.27, eight studies, 14,982 women, high quality evidence). There was significant heterogeneity in the duration of first stage of labour and the data were not pooled.

There was no clinically meaningful difference in Apgar scores less than seven at one minute (RR 0.96; 95% CI 0.84 to 1.10, seven studies, 14,924 women, high quality evidence). There was no clinically meaningful difference in Apgar scores less than seven at five minutes (RR 0.96; 95% CI 0.69 to 1.33, seven studies, 14,924 women, high quality evidence). There was no clinically meaningful difference in umbilical arterial pH between early initiation and late initiation (MD 0.01; 95% CI -0.01 to 0.03, four studies, 14,004 women, high quality evidence). There was no clinically meaningful difference in umbilical venous pH favouring early initiation (MD 0.01; 95% CI -0.00 to 0.02, four studies, 14,004 women, moderate quality evidence).

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