Mid-pregnancy causes back pain for the following reasons: First, pregnancy is a normal physiological process in women, can cause a series of changes in the body endocrine, resulting in aseptic inflammation occurs, the waist is located in the middle of the body, there are a large number of muscle tissues, myofibrillar inflammation can lead to the emergence of pain, generally to be physiotherapy, such as hot compresses and other conservative treatment to alleviate the symptoms; Second, lack of calcium is to produce back pain is another reason for the process of pregnancy in the fetus needs a lot of calcium, pregnant women consume calcium is also greater. Secondly, calcium deficiency is another reason for lumbar pain, in the process of pregnancy, the fetus needs a lot of calcium, pregnant women also consume a lot of calcium, so calcium deficiency is a common manifestation of the vast majority of pregnant women, which can produce the symptoms of lumbar pain, and need to supplement calcium in a timely manner; thirdly, the mid-pregnancy of abdominal cavity contents gradually increase in volume, strengthen the lumbar loading, lumbar muscles are very easy to strain, resulting in pain, need to allow pregnant women to pay attention to warmth, rest, and can be accompanied by physiotherapy, such as hot compresses to alleviate the symptoms. Symptoms.