Most pregnant women go into labor 24-48 hours after the onset of redness, while a few will go into labor 1 week after the onset of redness. Redness is a small amount of light red discharge from the vagina, and the corresponding symptoms can occur before labor starts, which is called preterm labor. In women, 24-48 hours before labor starts, the fetal membranes near the inner cervical canal and the uterine wall separate and the capillaries rupture, resulting in a small amount of blood flowing out and mixing with the mucus in the cervix to become light red, red or soy sauce colored, and within 24-48 hours after seeing red, the pregnant woman will start contractions to deliver the fetus. However, in a few cases, the contractions will not start until one week after the onset of redness. In addition, if a pregnant woman has more vaginal bleeding, she should consider other pathologies such as placenta abruptio and placenta praevia, etc. In this case, she should go to the obstetrics department of the hospital in time. In conclusion, redness is a reliable precursor to labor initiation, so pregnant women who experience redness need not be nervous and should be prepared for labor.