The dynamics of epidural and opioid analgesia during labour

To investigate the association of analgesia, opioids or epidural, or the combination of both with labour duration and spontaneous birth in nulliparous women.

A secondary data analysis of an existing cohort study was performed and included nulliparous women (n = 2074). Durations of total labour and first and second labour stage were calculated with Kaplan-Meier estimation for the four different study groups: no analgesia (n = 620), opioid analgesia (n = 743), epidural analgesia (n = 482), and combined application (n = 229). Labour duration was compared by Cox regression while adjusting for confounders and censoring for operative births. Logistic regression was used to investigate the association between the administration of different types of analgesia and mode of birth.

Most women in the combined application group were first to receive opioid analgesia. Women with no analgesia had the shortest duration of labour (log rank p < 0.001) and highest chance of a spontaneous birth (p < 0.001). If analgesia was administered, women with opioids had a shorter first stage (p = 0.018), compared to women with epidural (p < 0.001) or women with combined application (p < 0.001). Women with opioids had an increased chance to reach full cervical dilatation (p = 0.006). Women with epidural analgesia (p < 0.001) and women with combined application (p < 0.001) had a prolonged second stage and decreased chance of spontaneous birth compared to women without analgesia.

Women with opioids had a prolonged first stage, but increased chance to reach full cervical dilatation. Women with epidural analgesia and women with both opioid and epidural analgesia had a prolonged first and second stage and a decreased chance of a spontaneous birth.