Biochemical pregnancy usually occurs within 5 weeks of gestation. A biochemical pregnancy is an early miscarriage that usually occurs within 5 weeks of gestation. A biochemical pregnancy is one in which the sperm and egg unite but the fertilized egg is not successfully transported to the uterine cavity for implantation and passes out with menstruation. When biochemical pregnancy occurs, the body will show elevated serum human chorionic gonadotropin and positive urine pregnancy test, which are indicators suggesting that there is a pregnancy, but the gestational sac is not visible on ultrasonography. Most patients have no abnormal symptoms and think that their menstrual period is just delayed for a few days. Some women may experience vaginal bleeding and lower abdominal pain. Causes of biochemical pregnancy include physical weakness of pregnant women, old age, endocrine abnormalities, thin endometrium, polycystic ovary syndrome, endometrial polyps, habitual miscarriage, and poor sperm quality in men. Occasional occurrence of biochemical pregnancy usually does not affect normal conception in the future, but if it occurs frequently, it is necessary to identify the causes and actively intervene in the treatment.