The purpose of this study is to determine if intrathecal hydromorphone will relieve pain as well as intrathecal morphine after cesarean delivery, with fewer side effects.

Intrathecal morphine has long been the standard pain medication used in cesarean sections. Since some patients cannot tolerate morphine, hydromorphone may be an acceptable alternative. Intrathecal Intrathecal hydromorphone has been shown to be effective at treating post cesarean section pain and possibly with less side effects than morphine.

One side effect of morphine is respiratory depression occurring hours after the start of morphine use. Respiratory depression occurs when air being taken into the lungs is less than normal, leading to a lower amount of oxygen and carbon dioxide being exchanged in the blood stream. Because hydromorphone dosages are lower and it has a quicker onset of action than morphine, it is believed that the use of hydromorphone should decrease the possibility of delayed respiratory depression.

Inclusion Criteria:

• Scheduled for elective Cesarean sections under spinal anesthesia or combined spinal anesthesia
• ASA status of I-III
• BMI < 40
• Able to understand and sign informed consent

Exclusion Criteria:

• Severe pre-eclampsia
• Conversion to general anesthetic
• History of chronic opioid use
• Allergy to morphine, or hydromorphone
• Hyperemesis gravidarum
• Emergency case
• Patients who have an infection at the intended site of spinal insertion