This study will be a prospective randomized-controlled trial. It will take place at a single site at St. Mary's Health Center in Richmond Heights, Missouri. Pregnant women with a BMI ≥ 30 kg/m2 who will be undergoing non-emergent Cesarean sections for delivery will be eligible. Exclusion criteria will be patients who are undergoing emergency Cesarean section, patients who are in an immunosuppressed state (ie, HIV, cancer), if they have a pre-existing infection other than chorioamnionitis at the time of the Cesarean section, or have received steroids for more than two days. Chorioamnionitis will be defined by the presence of fever, uterine fundal tenderness, maternal tachycardia (\>100 beats per minute), fetal tachycardia (\>160 beats per minute), or purulent or foul-smelling vaginal discharge or amniotic fluid \[15\]. All Cesarean sections will be performed for standard indications and not for the purpose of the study. After informed consent is obtained in patients who choose to participate, patients will be randomly assigned to either the control group (conventional hand-held retractors used only) or to the treatment group (Alexis O C-section self-retaining retractor used as well as any hand held retractors that are deemed necessary by the surgeon). Both types of retractors are commonly used for cesarean sections in obese patients and the choice of retractor is made by physician preference. There will be no other differences between the two groups. Randomization will occur using a computer-generated randomization process prior to the start of the study and the individual assignments will be placed in opaque sealed envelopes. After a patient agrees to participate in the study, an envelope will be selected and opened to assign the patient to either the treatment or control group.

The Cesarean section will be performed for standard indications using standard surgical practice. All patients will receive pre-operative antibiotics according to St. Mary's Health Center standard practice. If the subcutaneous fat layer is \>2 cm, it will be closed with a suture layer as is accepted standard practice. Both of these measures have been showed to be associated with decreased risk of postoperative surgical site infection and are standard practice \[4, 16\]. The depth of the subcutaneous fat layer will be measured during the surgery using the sterile ruler that is provided as part of the standard Cesarean section surgical instrument tray set. If the patient is assigned to the Alexis retractor group, the Alexis retractor will be placed once the peritoneal incision has been made and extended adequately. The peritoneal incision is part of the usual surgical technique during Cesarean sections. The Alexis retractor will then be placed with the outer ring positioned external to the incision overlying the skin, the internal ring positioned inside the peritoneum against the anterior abdominal wall, with the connecting clear plastic barrier retracting the abdominal wall. The abdominal cavity will be palpated to ensure no abdominal organs have been inadvertently incorporated into the retractor as is the accepted protocol when using the Alexis retractor. All other aspects of the Cesarean section will be done routinely. Patients will be blinded to whether they were in the control or the treatment group. Postoperative care will be the same for both groups, according to standard practice. Patients will be followed until 30 days postpartum. They will be instructed to follow up for a postoperative incision check 1-2 weeks postoperatively. Patients will be contacted by telephone 30 days postoperatively to inquire if they have developed any type of surgical site infection in the 30 days postoperatively. They will be informed of this process during the consent process. Surgical site infections will be defined using the CDC criteria \[17\]. Information will be collected from the patient's hospital and clinic chart, including patient demographic information (patient BMI, maternal age, race, gestational age at delivery, number of previous surgeries, gravidity, parity, and maternal comorbidities); neonatal outcomes (infant weight, APGAR scores, need for NICU admission); indication for cesarean section; if the patient was laboring; the presence or absence of ruptured membranes (and length of time if ruptured membranes present); positive or negative GBS culture; the presence of chorioamnionitis; type of skin and uterine surgery; total duration of surgery and duration from skin incision until delivery of the infant; occurrance and type of infection; number of days postoperatively an infection occurred; depth of subcutaneous fat layer, estimated blood loss during surgery; change in hemoglobin from admission to postoperative Day #1 (a lab for hemoglobin and hematocrit drawn on postoperative Day #1 after a Cesarean section is part of routine care); requirement of intra-operative and postoperative anti-emetics; type of skin closure performed; length of postoperative hospital stay; presence of postoperative infection or wound disruption during hospital admission; the need for postoperative antibiotics; and other postoperative complications. Information will also be collected from the one to two week postoperative check, including presence of infection or wound disruption, need for postoperative antibiotics, need for wound opening or exploration, visits to the Emergency Room or need for hospital readmission. Information will be collected during the postoperative telephone call that occurs 30 days after the procedure. Participants will be asked the same questions which is on the attached question sheet, and includes whether the patient experienced a diagnosis of a postoperative infection, need for postoperative antibiotics, visit to the Emergency Room or hospital readmission, or other complication within 30 days after the Cesarean section.