1. Genetic factors: karyotype analysis of the couple’s karyotype.
2. Immune diseases: systemic lupus erythematosus, antiphospholipid syndrome, etc.
3. Reproductive tract anatomical abnormalities: uterine malformations (uterine septum, bicornuate uterus, unicornuate uterus), uterine adhesions, submucosal fibroids, endometrial polyps and cervical insufficiency, etc. Ma|, Infertility Treatment Center, Qilu Hospital of Shandong University
Endocrine abnormalities: thyroid disease, diabetes mellitus, polycystic ovary syndrome, luteal insufficiency and hyperprolactinemia, etc.
Reproductive tract infection factors (TORCH antibody, bacterial vaginosis, mycoplasma and chlamydia infection).
6. Thrombosis factors.
More than half of the patients with RSA cannot be found the cause of miscarriage.