This multicenter, prospective, randomized controlled clinical study examined 62 women who were scheduled to undergo an elective cesarean section at full term to compare the effectiveness and safety of postoperative intrathecal morphine at low and high doses.

Participants included full-term, singleton pregnant women aged 22 to 38 who were scheduled for cesarean delivery and weighed 55 to 80 kg. A total of 62 Chinese patients were divided into two groups, one receiving a low dose of Morphine (60 μg; N=32) and the other receiving a high dose (100 μg; N=30). The degree of post-cesarean pain was estimated at four, twelve, and twenty-four hours. Documentation of patients with side effects or those needing further rescue analgesic agents was done.

Age, height, weight, gestational age, or operation time did not vary between the study groups. At 4, 12, and 24 hours following cesarean delivery, there were no discernible differences between the two groups' resting and exercise pain intensities. Notably, 53 participants did not need further analgesics, indicating an overall success rate of 85.5% for the analgesics. The incidence of pruritus was lower in the low-dose group (13%) when compared to the high-dose group (40%). The other negative effects were reported to be similar for both groups.

For intrathecal analgesia, a single low-dosage 60 μg Morphine offered adequate post-cesarean analgesic effects, similar to a single high-dosage 100 μg Morphine.