Pregnancy biochemistry usually refers to the formation of a fertilized egg after the union of sperm and egg, but a spontaneous abortion occurs for various reasons. In clinical practice, this is often the case when a blood test for human chorionic gonadotropin reveals a pregnancy, but an ultrasound does not reveal a gestational sac, and when the level of the hormone is tested again, a decrease in the level of the hormone is found, which means that a spontaneous abortion has occurred, a condition called biochemical pregnancy. A biochemical pregnancy is a special type of miscarriage that is considered to be caused by an abnormal development of the embryo itself. It is recommended that if this happens, you should go to the hospital for relevant tests, except for biochemical pregnancies caused by chromosomal abnormalities in both spouses, so as not to affect the next pregnancy.