What are the reasons that can lead to habitual abortion in women?

Patient's question:

Will it cause women to suffer from habitual abortion? Took three years to have a child, lost four, still want to, must get pregnant

Doctor's answer:

First, immune factors. Pregnancy is similar to an allogeneic transplant, with a complex and special immunological relationship between the embryo and the mother, which prevents the fetus from being rejected. If the immune compatibility between the mother and fetus is poor, it can lead to the mother rejecting the embryo, resulting in miscarriage.
Second, anatomical abnormalities. These generally occur in the very early stages or during the second trimester, with the main causes being a uterine cavity, insufficient blood supply, and poor intrauterine environment. Anatomical abnormalities mainly include: uterine malformations, abnormal development of uterine arteries, cervical incompetence, and so on.
Third, genetic factors. This includes chromosomal abnormalities in both parents and the fetus. Miscarriage can occur at any stage of pregnancy, but is most common in the early stages. The main types are chromosomal abnormalities in the parents and the fetus.