SummaryThe use of volatile and gaseous anesthetics, of alkaloïds of opium and belladonna, ami of barbiturates, has not given to the obstetricans the results they expected in the domain of the obstetrical analgesia.Methods of blocking the semsory fibres coming from the uterus have been applied.The blocking at the height of the inferior anti superior hypogastric plexus remained without, result.Obstetricans limited themselves to the use of spinal anesthesia, caudal analgesia, and lumbar sympathetic infiltration, in most of the cases.The methods are not elective enough to allow the precise determination of the pathways of the nervous fibres to the uterus, and the most favorable place for their infiltration.Experimental observation has demonstrated that spinal anesthesia inferior to L1was useless, and that it was without influence upon the motricity of the uterus, if it did not reach the level D9.Similar observations have been made by Cleeland, among others, by using continuous caudal analgesia.The danger of spinal and caudal anesthesia are such, that, for the time being, we don’t make use of the bilateral lumbar sympathetic infiltration, as usual method of obstetrical analgesia.We make use of that infiltration at the level of L1, L2with 20 cc. of a solution of percaïne at 1°/°°.The study of 215 infiltrations demonstrated following points :1°Analgesia is perfect in 88,2 % of the cases.2°Duration of analgesia is of 4 hours average.3°Labour is modified very little. Now and then a stopping of the labour is noticed when the infiltration is made before a dilatation of 3 cm.4°No change concerning the period of dilatation, delivery and puerperium is noticed.