Nitrous oxide is a gaseous agent used as an analgesic in medicine. Being discovered in 18th century, it's wider use began in the middle of the 20th century after invention of anesthetic machine for the independent use of inhalation anesthetics. Although the mechanism of action of N2O is not completely clear, it is nowdays considered that its analgesic and anxiolytic effects are acheived by the release of endorphin in the central nervous system and the modulation of pain pathways by acting on different ion channels and receptors. As a 50% mixture of N2O and O2, it is suitable for use in obstetrics because of rapid action, rapid elimination from the body after cessation of use, and low levels toxicity for mother and child. It is used for analgesia and anxiolysis during childbirth and minor obstetric interventions. It carries a lower risk of side effects than epidural anesthesia and requires less invasive technique. Most common side effects are nausea, vomiting, vertigo and dysphoria. Previous research did not show negative impact of N2O analgesia on newborns. There has been a negative impact on health personnel exposed to small amounts of N2O over a long period of time, but with the use of modern ventilation and discharging systems, potential health problems of personnel are minimized.