Use of nitrous oxide in midwifery practice--complementary, synergistic, and needed in the United States.

50/50 mixture of nitrous oxide (N2O) and oxygen is a afe, inexpensive, and reasonably effective labor analgeic that is available and widely used and appreciated by omen in Canada, the United Kingdom (UK), Scandiavia, Australia, and many other parts of the modern estern world, but is not even known to most women in he United States, where it is offered in only a few ospitals. I became interested in N2O while directing a sympoium on The Nature and Management of Labor Pain. ystematic reviews of evidence regarding both the effeciveness and harms of virtually every method of labor nalgesia being used in the United States were presented t the symposium and published as a supplement to the ay 2002 issue of the American Journal of Obstetrics nd Gynecology. Dr. Mark Rosen’s paper on N2O was ased on findings from his systematic review and two ecades of personal experience providing N2O to women uring labor at Moffitt Hospital at the University of alifornia at San Francisco (UCSF). UCSF has recently dopted new guidelines that authorize midwives, as well s anesthesiologists, to teach and assist women to use 2O in labor 4 (see page 308).