Immersion in water during labor or delivery has been popularized over the past several decades. The prevalence of this practice in the United States is uncertain because it has not been studied in births outside of the home and birth centers, and the data are not recorded on birth certificates. Among randomized controlled trials included in a 2009 Cochrane systematic review that addressed immersion in the first stage of labor, results were inconsistent with regard to maternal benefits. Neither the Cochrane systematic review nor any individual trials included in that review reported any benefit to the newborn from maternal immersion during labor or delivery. Immersion in water during the first stage of labor may be associated with shorter labor and decreased use of spinal and epidural analgesia and may be offered to healthy women with uncomplicated pregnancies between 37 0/7 weeks and 41 6/7 weeks of gestation. There are insufficient data on which to draw conclusions regarding the relative benefits and risks of immersion in water during the second stage of labor and delivery. Therefore, until such data are available, it is the recommendation of the American College of Obstetricians and Gynecologists that birth occur on land, not in water. A woman who requests to give birth while submerged in water should be informed that the maternal and perinatal benefits and risks of this choice have not been studied sufficiently to either support or discourage her request. Facilities that plan to offer immersion during labor and delivery need to establish rigorous protocols for candidate selection; maintenance and cleaning of tubs and pools; infection control procedures, including standard precautions and personal protective equipment for health care personnel; monitoring of women and fetuses at appropriate intervals while immersed; and moving women from tubs if urgent maternal or fetal concerns or complications develop.