 Despite the generalized use of preoperative antibiotic prophylaxis, endometritis remains as the most frequent post-cesarean delivery complication. This increased morbidity translates into extended post-partum antibiotic use and prolongation of hospital stay with the subsequent increase in health care expenses. The current regimen recommended by the American College of Obstetricians and Gynecologists for cesarean delivery prophylaxis 1st generation cephalosporins does not cover for Ureaplasma Urealyticum, a microorganism that has been associated with an increased risk of endometritis in post-cesarean section patients. Azithromycin, an antibiotic that has both aerobic and some anaerobic coverage, uniquely covers Ureaplasma and would be an excellent second antibiotic for cesarean section chemoprophylaxis. Our hypothesis is that the addition of azithromycin to standard chemoprophylaxis with cefazolin can effect a 25 reduction of post-cesarean section endometritis. 