Influence of Entonox (mixture of 50% nitrous oxide and 50% oxygen) on physiological labor and neonatal outcome in own material.

We found that Entonox prolongs labor significantly and increases frequency of episiotomy in primiparas with no clear analgesic effect. Offering Entonox to the patients giving birth for the first time is thus questionable. In multiparas it has a good analgesic effect but increases probability of episiotomy with no significant influence on perineal tear, what seems not very high cost of decreased pain related to delivery.