Lumbar pain in 16 weeks of pregnancy may be caused by ligament involvement, sciatica, lumbar muscle strain and other reasons. 1. Ligament pulling: after 16 weeks of pregnancy with the increase of pregnancy weeks, pulling the surrounding ligaments, may trigger the surrounding state of congestion, pregnant women will have symptoms of back pain. 2. Sciatica: 16 weeks pregnant with the increase in pregnancy weeks, the spine will be along with the mother’s body changes forward protrusion, lumbar spine weight-bearing is more powerful, will lead to spinal discs move forward, stimulate the spinal nerves caused by sciatica, there will be a performance of low back pain. 3. Lumbar muscle strain: 16 weeks pregnant overwork, do too much physical labor, may cause lumbar muscle strain, resulting in muscle contracture, local muscle anaerobic metabolism, lactic acid increase will appear after the symptoms of lumbar pain. In addition, there are more reasons for lumbar pain in 16 weeks of pregnancy, such as trauma, lumbar disc herniation, visceral or pelvic diseases, physiological phenomena during pregnancy, etc. It is recommended that you visit the hospital in time for active diagnosis and treatment.