 Patients who meet inclusion criteria will be approached upon admission to Labor and Delivery. A study staff member will describe the study and offer participation. If a patient agrees to participate, she will sign research protocol and HIPAA consent forms and receive a copy of these forms. The patients chart will be flagged, indicating that she is a study participant. The patients prenatal care and labor and delivery will be managed by her physician per standard of care at the physicians discretion, including routine intrapartum treatment of Group B streptococcus GBS colonization using ampicillin. When a participating patient is diagnosed with chorioamnionitis, she will be randomized in a blinded fashion to Arm 1 Unasyn or Arm 2 ampicillingentamicin. She will be treated as per standard of care with tylenol, intravenous fluids, and her labor managed per physician discretion. From the time of diagnosis of chorioamnionitis until determination of treatment success or failure in the postpartum period, the patient will receive intravenous antibiotics per the protocol arm to which they have been assigned. If a patient has already been receiving ampicillin for GBS, the ampicillin will be discontinued when the study drugs are initiated. In arm 1, the study drugs will consist of Unasyn 3 grams intravenously every 6 hours, plus intravenous normal saline placebo dose every 8 hours. In arm 2, the study drugs will consist of gentamicin 1.5mgkg intravenously every 8 hours plus ampicillin 2gm intravenously every 6 hours. For all patients, clindamycin will be given intravenously at the time of clamping of the umbilical cord in the event of a cesarean delivery, and continued as part of the antibiotic regimen as per standard of care for cesarean section in the setting of chorioamnionitis. With the exception of the saline placebo doses, both the Unasyn regimen and the ampicillingentamicin regimen are efficacious and widely utilized regimens for the treatment of intrapartum chorioamnionitis, and do not represent a deviation from standard of care. After delivery, if the patient experiences a treatment failure as defined below, her medical care will be managed at the discretion of the attending physician as per standard of care, and her antibiotic regimen will be unblinded. After delivery, prior to discharge from the hospital, the patient will be asked to answer a short questionnaire enquiring about side effects experienced during treatment for chorioamnionitis. The patient may receive a phone call within 14 days of delivery to assess whether she has received treatment for postpartum complications at an outside institution after discharge from the hospital. 