After oxytocin injection, the uterine opening will gradually flatten and open along with regular contractions, but the timing of regular contractions varies from person to person, and a few pregnant women do not experience any change in the uterine opening after oxytocin injection. Oxytocin promotes contraction of the smooth muscle of the uterus during labor. The onset of oxytocin varies from person to person and may take about 11-12 hours to open fully in first-time mothers who are sensitive to oxytocin, while it may take 6-8 hours in menstruating mothers. Some pregnant women who are not sensitive to oxytocin will be accompanied by cervical edema and may fail to show opening of the uterus due to nervousness. In this case, pregnant women are advised to apply oxytocin for about 3 days, and if it still does not work, they may choose to end the pregnancy by cesarean section. In addition, since some pregnant women may experience nausea, vomiting and diarrhea after using oxytocin, they are advised to strictly follow the medical advice to avoid adverse consequences.