Effects of analgesics during labor.

Four analgesic agents were studied during labour: pethidinesparine, ketamine hydrochloride, nitrous oxide-oxygen, and trichloroethylene in air (Trilene). Excellent analgesia was achieved with ketamine, however hallucinations were troublesome. Trichloroethylene analgesia was good without side-effects. Pethidine-sparine produced moderate analgesia but with nausea and/or vomiting. Nitrous oxide 50% presented poor analgesia. Uterine activity was insignificantly diminished in the late first stage after administration of all analgesic agents except with ketamine. There were no untoward effects on fetuses.