Ideal methods for relieving the pain of childbirth have been the goal of obstetricians since ancient times. Inscriptions and drawings left by early Egyptians1 indicate that they tried unsuccessfully. Less than a century has elapsed since Sir James Y. Simpson of Edinburgh first used an anesthetic, a few drops of chloroform, for this purpose. In 1880 Klikowitsch introduced the use of nitrous oxide, a method popularized by J. Clarence Webster, Frank Lynch and Carl H. Davis of Chicago, and by Guedel of Indianapolis. Some years before, Steinbuchel, and Gauss of Germany, had suggested the use of scopolamine and morphine for alleviating labor pain, a method which under the name "dammerschlaf," or "twilight sleep," for a time was immensely popular. As originally employed, this method was soon discarded because of uncertain results, with an increase in maternal and fetal mortality. A modification of this method, however, is still widely used.