Results
infection, pain
INFECTION
Participants entered the study from July 2021 to January 2022. Of the 100 primiparous women who gave birth, 74 eligible women were randomly assigned to two groups (n = 37). Two women in the probiotic group refused to take drugs due to Covid- 19 infection and did not follow due to quarantine, and one was excluded from the study, due to unwillingness to continue the participation. Two persons in the placebo group were excluded from the study, due to non-referral on follow-up days, and the information of 69 women was finally analyzed (Fig. 
Flowchart of the studyThe mean (SD) age of women was 25.75 (5.48) in the probiotic group and 27.05(5.57) in the placebo group (P = 0.317). The mean (SD) of body mass index was 25.07 (3.72) in the probiotic group and 25.72 (2.58) in the placebo group (P = 0.387). The majority of participants in the probiotic (91.9%) and placebo (94.6%) groups were housekeeper. More than half of the participants in the probiotic (54.1%) and placebo (64.9%) groups were under diploma. Most of the participants (81.1% in the probiotic group and 78.4% in the placebo group) reported their family income as sufficient. The average number of skin sutures was 4.83 (1.11) in the probiotic group and 4.94 (0.99) in the placebo group (p = 0.662). In general, there was no statistically significant difference between the two groups in terms of demographic and obstetrics characteristics (Table 
The comparison of obstetrics and obstetrics characteristics between probiotic and placebo groupsHigh schoolDiplomaUniversity20(54.1)13(35.1)4(10.8)24(64.9)9(24.3)4(10.8)HousekeeperEmployedWorker34(91.9)1(2.7)2(5.4)35(94.6)1(2.7)1(2.7)Less than enoughEnoughMore than enough7(18.9)30(81.1)0(0)5(13.5)29(78.4)3(8.1)MidwifeObstetrics assistant13(35.1)24(64.9)11(29.7)26(70.3)† Mean (standard deviation),* Independent t-test, **Chi-squareThe mean (SD) score of wound healing in the probiotic group altered from 4.91(1.86) before discharge to 1.55 (0.99) during 5 ± 1 days after birth and reached to 0.95 (0.27) during 15 ± 1 days after birth. Further, the mean (SD) score of wound healing in the placabo group altered from 4.62(1.99) before discharge to 2.80 (1.20) during 5 ± 1 days after birth and reached to 1.45(0.71) during 15 ± 1 days after birth (adjusted mean difference [AMD]: -0.50, confidence interval [CI] 95%: -0.96 to -0.05, P = 0.03). The episiotomy wound had a healing process in both groups over time, which was significantly faster in the intervention group compared to the control group (Table 
The comparison of mean score of wound healing in probiotic and placebo groups over time†Adjusted mean difference after controlling the baseline score, *Independent t –test, **Repeated measures ANOVAThe mean (SD) score of used painkillers was 6.88 (2.73) in the probiotic group and 8.77 (4.04) in the placebo group (P = 0.141). Mean (SD) score of pain before discharge in the probiotic group changed from 4.05 (2.38) to 1.47 (0.64) on 5 ± 1 days after birth and 0.37 (0.17) on 15 ± 1 days after birth. Further, the mean (SD) score of pain before discharge in the placebo group decreased from 3.97 (1.44) to 1.95 (0.35) on 5 ± 1 days after birth and 0.46 (0.22) on 15 ± 1 days after birth, after controlling the effect of used painkillers (AMD: -0.09, CI 95%: -0.55 to 0.36, P = 0.66). Although the episiotomy pain improved during the wound healing process over time, no significant difference in pain perception was observed between the two groups during the intervention (Table 
The comparison of mean score of pain in probiotic and placebo groups over time†Adjusted mean difference after controlling the effect of used painkillers, *Independent t –test, **RMANOVA