There are many reasons why the due date is still not started late, the due date is 40 weeks pregnant, under normal circumstances, pregnant women without comorbidities or complications, more than the due date did not start contractions is a normal phenomenon, if more than 41 weeks have not started contractions, need to be evaluated to consider the induction of labor, pregnant women delayed contractions may be ovulation after the wrong, pregnant women with little exercise, cephalo-pelvic asymmetry, etc. Related to. 1. Ovulation error: the due date is calculated according to the first day of the last menstrual period, so the due date is only an estimate, such as ovulation error will lead to the calculation of the due date and the actual gestational week does not match, so this case will be more than the due date did not start. 2. little movement of pregnant women: due to the pregnancy, the amount of movement of pregnant women is small, the fetal prelude part of the slow descent, can not stimulate contractions caused by labor. 3. Cephalopelvic disproportion: The head of the fetus is bigger and the pelvis of the pregnant woman is smaller, which affects the downward movement of the fetal prelude and affects the birth of the baby. In late pregnancy, the doctor needs to measure the pelvis, and if there is cephalopelvic disproportion, a cesarean section is needed to terminate the pregnancy. If the due date is overdue, there is no need to worry too much, it is recommended to consult a doctor to develop an individualized treatment plan according to the specific situation, so as not to affect the health of the mother and baby.