Level 1: Causes of back pain in pregnant women 1. Back pain caused by physiological changes As pregnancy progresses, the body of pregnant women will undergo many physiological changes, such as enlargement, ligament relaxation, etc. These changes will affect the spine and pelvis, leading to Back pain. 2. Back pain caused by improper posture Pregnant women need to pay attention to their posture in daily life. If they maintain the same posture for a long time or the posture is incorrect, it will cause back pain.