[Analgesia during labour: from taboo to evidence-based medicine]

Peripartum care of parturients has contributed a great deal to the development of modern anaesthesia during the past 150 years. The introduction of general and regional anaesthesia provided new options of relieving pain during delivery and preventing suffering. However,provision of effective labor analgesia gave and still gives rise to controversy as to whether interfering with natural events such as delivery was justifiable on a religious,moral or ideological level. A new era of obstetric pain relief was initiated when a study design was devised to define the Minimum Local Analgesic Concentration (MLAC) needed for epidural analgesia. Using the MLAC model as a scientifically based pharmacodynamic measure of analgesia, empirically developed "recipes" can be compared and validated. The importance of this clinical model will be put into a pharmacological context including issues such as the up-down sequential allocation technique, dose-response curves and differential nerve blockade.