The purpose of this study is to determine if the addition of a 48-hour course of post-operative antibiotics to the recommended course of pre-operative antibiotics improves surgical site infection rate in patients who are obese and undergo Cesarean section after laboring.

The investigators propose the conduction of a prospective, randomized, double-blinded clinical trial to evaluate an alternative prophylactic regimen for the prevention of surgical site infection in women who are obese and have been laboring prior to their Cesarean section. This study is to be conducted by the Department of Obstetrics & Gynecology at John Sealy Hospital at the University of Texas Medical Branch in Galveston, Texas. The intervention being studied will be the administration of cephalexin and metronidazole post-operatively for 48 hours. The primary outcome measure will be surgical site infection (including superficial or deep incisional surgical site infection, endometritis, and other related infections, such as septic pelvic thrombophlebitis and abdominal or pelvic abscess) in the post-operative period.

In order to most effectively and accurately analyze our primary and secondary research outcomes, the investigators will standardize our surgical operation techniques in all ways feasible. These recommendations will be in concordance with American College of Obstetrics and Gynecology recommendations, as those generally accepted in the medical literature. All patients will undergo surgery in the same small group of HEPA-filtered and positive air-pressure operating rooms. Appropriate limitations on number of surgeons and assistants scrubbed for surgery, as well as general OR traffic, will be enforced. Patients will undergo hair clipping of the incision site when appropriate. Chlorhexidine skin decontamination will be the standard surgical site preparation. An adhesive drape will be used. Prior to skin incision, cefazolin and azithromycin will be administered.

All patients to be considered for recruitment to this study will be undergoing delivery at John Sealy Hospital at the University of Texas Medical Branch in Galveston, Texas. Patients with an elevated BMI >or =30 kg/m2 who undergo cesarean section after laboring will be considered for randomization either prior to delivery or in the first 7 hours after delivery, to accommodate the need for the first dose of study medication or placebo 8 hours after surgery. Only patients who agree to inclusion after informed consent will be randomized per protocol.

Inclusion Criteria:

• Women >18 and <50 years
• BMI >30kg/m2
• Decision by clinical team to perform Cesarean section
• Rupture of membranes (ROM) < 24 hours after onset of labor or during the course of labor (ROM defined by spontaneous or artificial rupture of the amniotic sac)

Exclusion Criteria:

• Subject unwilling or unable to provide consent
• No prenatal care or a non-UTMB subject who is unlikely to be followed up after delivery
• Fetal demise or major congenital anomaly
• Immunosuppressed subjects: i.e., taking systemic immunosuppressants or steroids (e.g. transplant subjects; not including steroids for lung maturity), HIV with CD4<200, or other
• Diagnosis or suspicion of chorioamnionitis prior to randomization
• Other planned post-operative antibiotic administration
• High likelihood of additional surgical procedure beyond cesarean (e.g. scheduled hysterectomy, bowel or adnexal surgery)
• Known allergy or contraindication to cephalosporins or metronidazole
• Incarcerated individuals

Double blinded