Seven months of pregnancy causes pain in the left side of the buttocks, mainly because of the weight gain after pregnancy and increased intra-abdominal pressure, which leads to the aggravation of lumbar disc herniation or the degeneration of lumbar discs themselves. Herniated discs due to the above reasons will in turn compress the nerves, leading to radiating pain in the muscles of the innervated area. If the compression is prolonged or severe, numbness or muscle atrophy in the innervated area may occur. The most common types of herniated discs are lumbar 4 and 5 or lumbar 5 sacral 1 discs, which compress the lumbar 5 nerve root and sacral 1 nerve root, respectively. Both of these nerve roots innervate the muscles of the buttocks, and if they are compressed, buttock pain will occur. For the above situation, we should improve the MRI examination, after clear diagnosis, most patients can use bed rest, with lumbar spine traction or lumbar spine massage, but also with localized hot compress treatment, so as to get cured.