Pregnancy with adenomyosis does not cause low HCG. HCG (human chorionic gonadotropin) is secreted by the trophoblast cells of the placenta, and the level of HCG increases as the pregnancy progresses.Low HCG is most commonly seen when the embryo is stunted or in the early stages of pregnancy, and is also common in ectopic pregnancies. Adenomyosis is a disease caused by the invasion of endometrial glands and mesenchyme into the myometrium of the uterus, which is characterized by prolonged menstrual periods, increased menstrual flow, and progressively worsening dysmenorrhea. Adenomyosis does not have a direct effect on HCG levels after pregnancy, so if low HCG is present, it is still important to first improve ultrasound and other tests to rule out the above conditions. In conclusion, it is recommended to consult a doctor for standardized diagnosis and treatment if necessary.