Epidural analgesia (EA) is the gold standard for pain relief during labour and delivery. In spite of its efficacy and increased use there has been significant controversy regarding its impact on labour outcomes. the current evidence suggests that EA does not increase the overall rate of caesarean delivery,¹ however, its impact on operative vaginal delivery and neonatal outcome is still not that clear. ^{2 3} Characteristics such as multiple birth, preterm labour, foetal presentation, spontaneous versus induced labour, and previous uterine surgeries may impact labour progress and maternal as well as neonatal outcome. Many of these characteristics have not been adequately accounted for in randomized trials published to date, since smaller sub-groups of labours (e.g. breech or twin labour) have not been adequately represented in these trials due to their relatively small contribution to the overall number of deliveries.^4–7

Ten-Group Classification System (TGCS) was first described in 2001 and originally utilized to assess caesarean delivery rates.⁸ the TGSC is structured to make it relevant to clinicians and labouring women, and to provide a common language for discussion on safety, quality of care and perinatal audit.⁹ the TGCS has been endorsed by the World Health Organization and the International Federation of Gynecology and Obstetrics and is increasingly used by labour and delivery units to report their caesarean delivery rates.^10–13 It was also recommended that other events and outcomes surrounding labour and delivery are analysed using this classification.^11–13

This manuscript presents the data recently published in IJOA showing the effects of EA on labour and delivery outcomes in Slovenia using the Slovenian National Perinatal Information System (NPIS) data for the period 2007 through 2014.¹⁴ the TGCS (table 1) was used to assess the difference in caesarean deliveries and operative vaginal deliveries between women with or without EA during labour.

Two hundred seven thousand five hundred deliveries fulfilled inclusion criteria. table 2 presents numbers of deliveries in women who did and did not receive EA according to the TGCS labour types. Basic maternal (age, BMI) and neonatal (birth weight, occipito-posterior presentation) characteristics that could act as confounders in the analysis of incidences of caesarean and/or operative vaginal delivery rates are also presented for each of the groups. Statistically significant differences in maternal age, BMI, birthweight and rates of occipito-posterior presentation were found in most groups 1 to 5 (table 1). table 3 shows count and percentages of caesarean deliveries and operative vaginal deliveries in the group of women who received EA during labour vs. those who did not. the caesarean delivery rates were lower among women with EA versus women without EA in all the TGCS groups except in group 3 (multiparous term women with singleton foetuses in cephalic presentation in spontaneous labour) in which caesarean delivery rates were very low irrespective of analgesic technique, group 9 (abnormal lies) in which caesarean delivery rates were high irrespective of analgesic technique, and group 1 (nulliparous term women with singleton foetuses in cephalic presentation in spontaneous labour). In group 1 EA was associated with significantly higher caesarean delivery rates in contrast to other groups. the potential association between EA and caesarean delivery is complex and difficult to study in observational studies. This may also explain the conflicting results of several studies published on this topic to date.¹ EA as an effective analgesic method may have a beneficial effect on labour progression and therefore lower the risk of dystocia and, consequently, caesarean delivery. the seemingly consistent association between EA and lower caesarean rates in most groups of labouring women seems to support this hypothesis. on the other hand, the request for EA may be a marker of dysfunctional (prolonged or obstructed) labour, since women with complicated labours are more likely to require more efficient analgesia. the higher caesarean delivery rates in group 1 may be the result of such an association.³ Future studies on the characteristics of nulliparous women requesting EA should be performed to elucidate this, since preventing cesarean delivery in this group of women is a very important goal.¹⁵

The rate of operative vaginal delivery was higher in women with EA in groups 1 to 5 (table 1). An association between EA and higher operative vaginal delivery rates was observed in most TGCS labour types, and this in accordance with several previously published studies that showed an overall increase in operative vaginal delivery rates with EA.^{3 4 15} This may be, in part, explained by a higher incidence of occipito-posterior presentation possibly due to the then EA practice of delivering either single boluses or constant infusions alone or combined with patient controlled boluses of higher local anaesthetic concentrations without fentanyl with a consequently higher potential of motor blockade during the study period.^{3 15} It also has to be noted that obstetricians were not blinded to the type of analgesia present and may be more likely to perform an operative vaginal delivery in women with EA. Moreover, higher neonatal birth weights observed in EA groups may also have contributed to higher operative vaginal delivery rates associated with EA.

In conclusion, when looking for associations between the use of EA and different rates of labour interventions, the TGCS groups should be taken into consideration. Epidural analgesia was associated with a higher caesarean delivery rate in nulliparous term women with singleton foetuses in cephalic presentation in spontaneous labour (group 1), and with higher vacuum delivery rates in most TGCS groups.

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