Abstract: We included four trials involving 388 women that were judged to be at an unclear to high risk of bias overall. A variety of different agents for providing analgesia were assessed in the trials, and a number of different methods to measure pain relief were used, and thus results could not be combined in meta-analysis. Three trials compared diazepam with an alternative agent (ketamine; vinydan-ether; "other" anaesthesic agent) for the provision of general anaesthesia, and one trial compared spinal analgesia to pudendal nerve block (in both groups lignocaine was administered). With regard to the primary outcomes, women receiving diazepam for forceps delivery in one small trial were more likely to judge their pain relief as effective compared with women receiving vinydan-ether (risk ratio (RR) 1.13; 95% confidence interval (CI) 1.02 to 1.25; 101 women). In a further small trial, no significant difference was seen in the number of women judging their pain relief as effective when diazepam was compared with ketamine (RR 1.42; 95% CI 0.98 to 2.07; 26 women). In the trial that compared spinal analgesia to pudendal nerve block, women receiving spinal analgesia were significantly more likely to regard their analgesia as adequate (RR 3.36; 95% CI 2.46 to 4.60; 183 women) and were less likely to report severe pain during forceps delivery (RR 0.02; 95% CI 0.00 to 0.27; 183 women). No trials reported on the review's other two primary outcomes of serious maternal adverse effects or complications, and neonatal mortality or serious morbidity. In terms of secondary outcomes, women receiving diazepam compared with vinydan-ether, were significantly less likely to experience vomiting (RR 0.04; 95% CI 0.00 to 0.62; 101 women). No significant differences were seen for the few neonatal outcomes that were reported across any of the comparisons (including Agpar score of less than seven at five minutes and acidosis as defined by cord blood arterial pH less than 7.2). There is insufficient evidence to support any particular analgesic agent or method as most effective in providing pain relief for forceps delivery. Neonatal outcomes have largely not been evaluated.

Plain-language summary: This review found that there is not enough evidence from the four included randomised controlled trials, involving 388 women and their babies, to determine the most effective and safe analgesic agent or technique for women who are undergoing a forceps delivery. Three of the four trials compared diazepam with alternative agents (ketamine, vinydan-ether, or "other" anaesthesic agent) to provide general anaesthesia during forceps delivery. A number of different methods were used to measure pain relief and the results could not be combined. The data from one trial could not be included in the review. Women who received diazepam were more likely to judge their pain relief as effective compared with women who received vinydan-ether in one small trial. In another small trial, however, no difference in pain relief was shown when diazepam was compared with ketamine. In the trial that compared spinal analgesia with pudendal nerve block, women receiving spinal analgesia were more likely to report their pain relief as adequate and were less likely to report severe pain. None of the four trials reported on serious complications or death for the mother or baby. The included trials had a high or unclear risk of bias and were not of a high quality. Each of the four included trials was conducted prior to 1980 and assessed agents or methods that are not commonly used in clinical practice today. Therefore, more studies are needed to establish what drug, or technique, is most effective and safe in reducing pain for the mother. These studies should also assess safety for the baby.