Efforts to relieve pain and provide comfort for mothers giving birth non-pharmacologically, one of which is using warm compresses. The purpose of this study was to determine the effect of warm compresses on reducing the intensity of back pain in third trimester pregnant women at PMB D in South Jakarta City in 2022. The research method used a pre-experimental design with a one group pretest posttest design. The number of samples is 30 respondents. The population of this study were all third trimester pregnant women with a sampling technique that was purposive sampling. Data collection techniques used questionnaires and the NRS pain scale. Data analysis used Wilxocone test and paired t test. Results of the Wilcoxone study From the results of the Wilcoxon test, it was found that the negative ranks were higher than the positive ranks, which meant that there was a decrease after being given treatment. From the statistical results obtained a Z value of -4.452 and an asymp.sig (2-tailed) value of 0.000, which means it is smaller than 0.05 so that the data is accepted which means that there is an effect between before and after applying warm compresses. Then the results of the paired t test found that the average back pain before applying warm compresses was 6.80 while the average pain after applying warm compresses was 3.83. These results indicate that there is a decrease in back pain before and after with a difference of 2.97 and a significant result of 0.000 is obtained, which is less than the significant level of 5% (p-value = 0.000 <0.05), so the conclusion is that Ha is accepted, which means that there is an effect of giving warm compresses on the intensity of back pain in third trimester pregnant women. The results of the study suggest that warm compresses can be used as an alternative non-pharmacological therapy in the management of back pain in third trimester pregnant women.