The reasons for bad pregnancy may be related to uterine developmental abnormalities, polycystic ovary syndrome, reduced sperm motility and other factors. 1. Abnormal uterine development: it is a kind of congenital malformation of reproductive organs, usually asymptomatic, often found in pregnancy, manifested as naïve uterus, unicornuate uterus or stumpy uterus. When uterine malformation occurs, sperm and semen can’t get in, or the fertilized egg is not suitable for implantation in the uterus, which leads to bad pregnancy. 2. Polycystic Ovary Syndrome (PCOS): it is a kind of secretion and metabolic disease, which is a common disease among women in their reproductive years, and it can lead to hirsuteness, abnormal menstruation, and poor pregnancy. It is due to the fact that several eggs develop at the same time, and the mature eggs can not be discharged, and there is an obstruction of ovulation, so that the eggs can not combine with sperms during the ovulation period, which leads to poor pregnancy. 3. Weak spermatozoa: due to men staying up late for a long time, living an irregular life, and being in an environment with too high a temperature, it can cause a decrease in sperm activity, clinically known as weak spermatozoa, which has low sperm vitality, difficulty in moving forward, and difficulty in passing through the cervical canal, so the fertilized egg can’t be combined, resulting in a bad pregnancy. There are many clinical reasons for not getting pregnant, so you should consult a doctor in time to find out the cause of the disease and treat the symptoms under the doctor’s guidance.