The objective of the study was to assess the effect of suboptimal second-stage pain control on the risk of difficult delivery.

We conducted a secondary analysis of the Pushing Early Or Pushing Late with Epidural (PEOPLE) randomized, controlled trial cohort on second-stage nulliparous women. We defined suboptimal pain control as a visual analog pain scale score of 30 or greater on a scale of 100 and evaluated initial postrandomization and subsequent pain control on obstetrical interventions and outcomes. We estimated adjusted relative risk for caesarean delivery using logistic regression models to control for confounding variables and to evaluate the role of effect measure modifiers.

One thousand seven hundred fifty-six women were included in the cohort, of which 1565 (89.1%) had optimal analgesia and 191 (10.9%) had suboptimal analgesia. Women with suboptimal analgesia had an increased risk of cesarean delivery of 2.97 (1.52-5.80), midpelvic procedures of 1.83 (1.10-3.05), and third- and fourth-degree perineal tears of 1.82 (1.03-3.21). As compared with women with sustained optimal analgesia, increasing levels of pain were associated with an increase in difficult deliveries, 2.19 (1.50-3.21). The improvement of relief among women with initial suboptimal initial analgesia did not alter the risk of difficult deliveries.

Although most women achieve optimal epidural analgesia, the inability to sustain optimal epidural analgesia is associated with an increased risk of adverse second-stage obstetrical outcomes.