Abstract： Objective To explore the application of painless delivery combined with analgesics in primiparous delivery analgesia and its effects on lactation function and pain mediators.Methods 96 full-term primiparous women admitted to Changzheng People's Hospital of Shangqiu from January 2021 to January 2023 who were scheduled for painless delivery were randomly divided into an observation group and a control group,with 48 cases in each group.The control group underwent painless delivery under ropivacaine epidural anesthesia,while the observation group underwent painless delivery under ropivacaine combined with sufentanil epidural anesthesia.Compare the perinatal related indicators[first stage of labor time,second stage of labor time,third stage of labor time,analgesic onset time,complete analgesia block time,analgesic duration,postpartum bleeding volume]and lactation function indicators[colostrum time,lactation score at 24 hours postpartum,and serum prolactin(PRL)levels before delivery(T1),30 minutes postpartum(T2),and 24 hours postpartum(T3)]between the two groups.Take the first stage of labor(t1),the second stage of labor(t2),and the third stage of labor(t3)as the time points,compare the VAS scores,pain mediator indicators[substance P(SP),prostaglandin E2(PGE2),norepinephrine(NE)],and maternal and infant outcomes between the two groups.Results The first and second stages of labor,analgesic onset time,and complete analgesia block time of the observation group were all shorter than those of the control group,and the duration of analgesia was better than that of the control group(P＜0.05);the observation group had shorter colostrum time than the control group,and the lactation score at 24 hours postpartum was higher than the control group,the prolactin levels at time points T2 and T3 were higher than the control group(P＜0.05);the VAS scores of the observation group were lower than those of the control group during the t1-t3 time period(P＜0.05);the levels of SP,PGE2,and NE in the observation group were lower than those in the control group during the t1-t3 time period(P＜0.05);the postpartum bleeding volume in the observation group was lower than that in the control group,and the 1-minute Apgar score of newborns was higher than that in the control group(P＜0.05);the puerperal infection rate in the observation group was 2.08%,and there was no statistically significant difference compared to the control group of 6.25%(P＞0.05).Conclusion The application of ropivacaine combined with sufentanil in painless delivery can effectively regulate the level of pain mediators,improve the quality of pain relief,promote the recovery of lactation function,and improve maternal and infant outcomes.