Less is more: the recent history of neuraxial labor analgesia.

Labor analgesia researchers have pursued better and safer ways to provide pain relief in labor. Although some pharmacologic investigations have focused on alternative mechanisms to target and medications to employ, a large part of the recent obstetric anesthesiology literature has contributed toward the safety and efficacy of techniques dependent on traditional therapeutics, specifically local anesthetics given through a neuraxial anesthetic technique. Investigators have worked to demonstrate and remove doubts that neuraxial anesthesia can be a safe method of labor analgesia. Pharmacodynamic studies during the last 3 decades have revealed ways to achieve adequate analgesia with minimal doses and correspondingly minimal risks. Dose-sparing opiate adjuncts to local anesthetics are now commonplace. To avoid excessive dosages, clinical up-down sequential allocation experiments identified the minimum amounts of local analgesia needed. Modifications to the administration of drug allowed total doses to be further reduced. This historical overview highlights some of these important advances in the present and recent past of neuraxial labor analgesia, and it traces how desired outcomes are being achieved with less and less total drug.