Group of 181 patients that will receive supplemental oxygen 80% FIO2 during surgery (cesarean) and two hours after the procedure.

Group of 181 patients that will not receive supplemental oxygen during surgery (cesarean).

Use of oxygen 80% FIO2 during surgery and 2 hours after the procedure. For this purpose an oxygen mask with reservoir will be used (to guarantee the supply of 80% oxygen during and after surgery)

The patients will be evaluated for evidence of surgical site infection before leaving the hospital, at 15 and 30 days post surgery. The presence of fever, supurative secretion through the wound or cutaneous changes compatible witn infection will be considered a surgical site infection (SSI). This outcome will be evaluated with a qualitative variable (presence of SSI). The patients will be clasiffied in accordance as "With SSI" or "Without SSI". This will allow us to determine if the use of oxygen at 80% FIO2 can reduce the incidence of SSI.

Every patient will be evaluated during surgery and before leaving the hospital for signs of a respiratory complication (persistent cough, fever, dyspnea, atelectatic rales, wheezing). The presence of any of these signs will be used to classify the patients with a qualitative variable ("With Respiratory Complications" or "Without Respiratory Complications") and allow us to determine if the use of oxygen at 80% FIO2 is associated with more respiratory complications.