[From balanced analgesia to epidural analgesia or combined spinal-epidural analgesia for relief of labor pain].

The trial of labor analgesia in Japan dates back to the year 1929. After the foundation of the original Japan Society of Obstetric Anesthesia and Perinatology in 1961, various labor analgesia techniques were widely attempted. Some anesthetists relieved the labor pain with balanced anesthesia using intravenous (diazepam and pethidine during the 1st stage of labor, followed by pentobarbital or ketamine during the 2nd stage of labor) combined with inhalational anesthetic (methoxyflurane or enflurane), while the others tried regional anesthesia. In 1990's, epidural analgesia with bupivacaine became more popular as a standard method of labor analgesia. Recently, the choice of local anesthetic has changed to ropivacaine or levobupivacaine, and in most cases combined with an opioid. Combined spinal-epidural analgesia or patient-controlled epidural analgesia has also been accepted in some hospitals, because these techniques may lessen the total consumption of local anesthetics and also induce mothers' satisfaction. However, the ideal labor analgesia technique has been still controversial. We, obstetric anesthesiologists, should grope for safer and more comfortable anesthetics to the mother and fetus. In next 50 years, the standard method for labor analgesia may change to no needle system with non-placental transfer anesthetics.