There is no scientific basis for determining whether there are more sons or daughters born after the due date. Women according to the time of the last menstrual period can be projected to the expected date of delivery, in the expected date of delay or two weeks in advance of the time of delivery is a normal phenomenon, more than the expected date of delivery can not be judged to be more sons or daughters, there is no scientific basis for this. More than the due date has not been born may be pregnant women’s body hormone ratio imbalance, estrogen to stimulate the production of prostaglandins, increase the uterus to the sensitivity of the contraction of the uterus, to promote cervical ripening. Progesterone reduces prostaglandin synthesis and decreases the sensitivity of the uterine myometrium to contractions. Low levels of estrogen and high levels of progesterone in the pregnant woman’s body will prevent her from having a baby beyond her due date. Late pregnancy there is a fetal head is too large, fetal position is not correct, fetal deformity and other conditions, fetal preluxation site of the lower uterine segment or cervical stimulation is relatively low, will result in more than the expected date of birth is not produced. Usually do a good job of maternity checkups during pregnancy, and go to the hospital in time to wait for labor if there is no movement of labor after 41 weeks of pregnancy.