Study aim: Comparison of the effect of infrared belt with hot water bag on pain intensity and duration of first stage of labor in primiparous women Design: Clinical trial with control group, parallel groups, randomized without blinding Settings and conduct: The study site is Mashhad Hospital, Mashhad. Sampling is easy. In both groups, the intervention was performed in two cycles for 20 minutes, in the lumbar region of mothers in the first stage of labor, in 4-5 cm dilation and then in 6-7 cm dilation. The duration of the contractions, the severity of the contractions, are recorded and recorded every 10 minutes every half hour. The mean score of pain intensity in the intervention groups was measured by the researcher in the first stage of labor, immediately after the uterine contraction, before the first intervention cycle, and immediately after the two intervention cycles, and at the end of the first phase of labor, ie, 10 cm dilation of the cervix. . . Participants/Inclusion and exclusion criteria: Inclusion criteria: be Iranian. • The age of delivery is 18-35 years. • Be literate. • be primiparous. • singleton is. • Show fetal head peak. • Exclusion criteria: • Have drug and alcohol addiction and tobacco. Mother discontinued from continuing research. Emergency caesarean section is indicated for any reason. • Affected by medical conditions Intervention groups: This study included two intervention groups (infrared belt and hot water bag) and one control group. Main outcome variables: Severity of labor pain, duration of first stage of labor