When a woman has a biochemical pregnancy followed by secondary infertility, there are three main reasons for this situation: First, the patient’s last pregnancy and miscarriage was not a true biochemical pregnancy, but an ectopic pregnancy. Even if the patient has an ectopic pregnancy and the gestational sac is not active, the presence of the gestational sac or mass is not detected by ultrasound, so it may be mistaken for a biochemical pregnancy in the clinical setting. However, in fact, there is a problem with the fallopian tube and an ectopic pregnancy has occurred locally, but the embryonic tissue is not active and has died and absorbed on its own. If the patient’s fallopian tube is not open, it will affect the patient’s pregnancy and may lead to secondary infertility. Secondly, we should consider that the endometrium of the uterus is damaged after the miscarriage of biochemical pregnancy, resulting in damage to the endometrium or endometrial adhesions, which affects the fertilized egg’s implantation and therefore leads to secondary infertility. Thirdly, the patient may have problems of her own, such as positive anti-sperm antibodies and anti-endometrial antibodies, or immune system diseases, or problems with sperm and egg quality, etc., resulting in biochemical pregnancy or secondary infertility. It is necessary to do a thorough physical examination according to the other clinical symptoms and signs of the patient to find out the cause and treat the symptoms.