There are many cases that cannot be delivered by normal delivery, mainly including fetus and maternal aspects. The fetal factors: 1, the fetus is too large: the fetus in the uterus is too large, resulting in greater difficulty in vaginal output, and easy to cause lacerations in the birth canal and even cause obstructed labor; 2, fetal position: when the fetal position before delivery is breech first dew, the fetal hip is smaller than the circumference of the fetal head, softer, the birth canal can not be fully expanded, the fetal head delivery is more difficult, easy to cause obstructed labor; when the fetal position is shoulder When the fetal position is shoulder first, the fetal body is perpendicular to the pelvis, the full-term fetus cannot pass through the birth canal and the normal delivery is very threatening to the mother and child; 3, fetal malformation: abnormal development of a part of the fetus, such as hydrocephalus, conjoined twins, etc., because the fetal head or fetal body is too large, it is often difficult to pass through the birth canal and cannot be delivered by normal delivery; 4, fetal distress: the fetus has signs of oxygen deprivation in the uterus, which endangers the health and life of the fetus and requires active cesarean delivery and should not be insisted on. 5, placenta, fetal heart abnormalities: such as placenta abruptio, placenta praevia or abnormal fetal heart sounds, suggesting that the situation is serious, need to carry out cesarean delivery to ensure the safety of mother and child. Maternal factors: 1, the maternal pelvis is small: small pelvis is narrower, the pelvic inlet is smaller, not conducive to fetal output from the vagina; 2, more amniotic fluid: too much amniotic fluid when the uterine tension increases, affecting the pregnant woman’s rest, and make her blood pressure rise, coupled with high uterine cavity, abdominal cavity pressure increases, serious heart failure can cause pregnant women, is not conducive to the fetal delivery; 3, psychological stress factors: maternal social Psychological factors can cause a series of changes in the body to affect the force of delivery, is also one of the important factors to determine whether the delivery can be; 4, other: high-risk maternity, older women or women with serious other organ comorbidities, etc., is also one of the factors that can not be smooth delivery.