Intrathecal (IT) opioids are commonly administered with local anesthetic during spinal anesthesia for post-Cesarean delivery analgesia. Traditionally, IT morphine has been used but the use of IT hydromorphone is growing. A previous study has shown that the effective dose for postoperative analgesia in 90% patients (ED90) for both IT hydromorphone and IT morphine (NCT02009722). These doses were found to be 75 mcg for hydromorphone and 150 mcg for morphine. The current proposed study would compare the duration of analgesia of IT morphine vs IT hydromorphone after elective cesarean delivery. Additionally, the investigators will compare each drug with respect the incidence of nausea and pruritus.