Biochemical pregnancy means that the sperm-egg has united, usually the sperm-egg will secrete chorionic gonadotropin after seven days of union, and after another seven days, it can be detected by the early pregnancy test, often the sperm-egg has united and secreted, but it must unite into a fertilized egg, and the fertilized egg has to return to the uterus to be laid. Biochemical pregnancy. The main reason is that the embryo does not develop well and the chromosomes are not normal. This is more common in some women who are undergoing IVF. However, most women ignore it as a delayed period because they did not go to the hospital for examination and they do not care about it, but in fact it is already a spontaneous miscarriage. Do not be alarmed if a woman of age encounters such a situation, as it is the result of natural elimination and usually does not affect the next pregnancy. If this happens repeatedly, it is time to go to the hospital for further examination.