Second-trimester pregnant women, or menstruating mothers, tend to go into labor after delivery. Some pregnant women have already entered the pelvis in late pregnancy, so there is no necessary connection between the time of entering the pelvis and the time of delivery. Pelvic delivery means that the head of the fetus passes through the mother’s pelvis and enters the pelvic cavity, which is usually manifested by the mother’s consciousness of fetal descent, upper abdominal comfort and symptoms such as frequent urination and abdominal pain. The fetus may be in labor before or during labor. The fetal head is often high and floating and not in the pelvis, but it can be passively in the pelvis by the force of labor, so the progress of labor is not related to whether the fetal head is in the pelvis or not. The time needed to enter the delivery stage varies with the condition of the pregnant woman and the time needed to enter the pelvis. If a pregnant woman with a second child has regular contractions, even if the fetal head is not in the pelvis, she should be sent to the doctor in time for delivery and attention should be paid to any abdominal pain, redness and other symptoms.