Hydromorphone group:Hydromorphone 15µg/ml combined with 0.08% ropivacaine for epidural analgesia

Comparison of equivalent hydromorphone and sufentanil combined with ropivacaine for continuous epidural labor analgesia: a randomized, parallel-controlled, non-inferiority trial

Effects of ropivacaine combined with different opioids for labor analgesia on maternal intrapartum temperature: a randomized, double-blind, parallel-controlled, multicenter study