Biochemical pregnancy is a spontaneous miscarriage within 5 weeks of pregnancy, when progesterone is elevated, urine test is positive, but the gestational sac is not visible on ultrasound, and the fertilized egg fails to implant, also known clinically as “subclinical miscarriage”. Because the timing is similar to the menstrual cycle, many biochemical pregnancies go unnoticed, thinking that the period is delayed for two days and then comes back. The following symptoms are usually present in pregnancy biochemistry: 1. Early pregnancy test is usually weakly positive, with two light bars. 2. 2. Menopause and low blood HCG value, which can only indicate pregnancy, but not whether it is successfully bedded or not. 3.The ultrasound examination cannot see the pregnancy sac. 4.Usually it will not be more than 50 days to miscarry spontaneously, there will be grayish white membranous flow out. 5.There is vaginal bleeding and the abdomen is not very painful, it feels like experiencing a menstrual period. The biochemical pregnancy is a natural eugenics of the fetus, biochemical pregnancy is not uncommon, accounting for about 25%-30% of total pregnancies, there is no need to be too afraid, the specific symptoms are like experiencing a menstrual period, usually will not affect the next pregnancy, but if the phenomenon of biochemical pregnancy occurs many times, it is recommended to consult the reproductive center for further examination and treatment. Be alert to the occurrence of habitual biochemistry.