The symptoms of redness during pregnancy may be caused by the following factors: 1. If the symptoms of redness appear in early pregnancy, it may be caused by low progesterone in the body or by factors such as overexertion in early pregnancy, resulting in preterm miscarriage. 2. The woman’s symptoms of redness near the due date are normal and are a normal manifestation of pre-birth. This is because the cervical opening will dilate before delivery, and the fetal membrane tissue near the inner cervical opening will peel off from the uterine wall, causing the capillaries to rupture and cause redness.