What is the cause of pregnancy HCG low?

HCG level is low, generally indicating that there is a problem with embryo development. In the early stages of pregnancy, HCG is generally low, but with the extension of pregnancy, HCG in the blood will gradually increase, usually within 48 hours will double, showing bleeding HCG does not double normally need to do further examination. Common reasons are: 1. Abnormal fetal chromosomes, this accounts for more than 50%. 2. Maternal factors, such as uterine malformations, viruses, bacterial infections, etc., can cause fetal dysplasia.