Cohort of Patients Presenting Unexplained Recurrent Miscarriages and Identification of Early Miscarriage Recidivism Factors

About 1 to 3% of women of childbearing age suffer repeated early spontaneous miscarriages (RCF) defined by at least 3 fetal losses before 14 weeks of gestation. RCFs may be linked to parental chromosomal abnormalities, congenital or acquired uterine abnormalities, hormonal causes (e.g. type 1 and 2 diabetes, ovarian failure), infectious etiology, constitutional or acquired thrombophilia or sickle cell disease.

The presence of antiphospholipid antibodies, antithyroid and anti-transglutaminase antibodies in approximately 10% of cases suggests an autoimmune origin for these fetal losses. The role of other antibodies, in particular non-conventional antiphospholipid antibodies, remains to be established. Indeed half of RCF cases are thought to be due to an immunological dysregulation of the mother leading to a decrease in tolerance to the fetus. Several studies have shown immune abnormalities, such as an imbalance of pro and anti-inflammatory cytokines, an increase in cytotoxic cells and a defect in regulatory cells in the blood of patients. The assessment of these immune abnormalities is not currently performed routinely in France in women presenting with recurrent early miscarriages. When one of these known causes is excluded, it is unexplained RCF which represents 50% of RCF. Over half of these women with RCF may be linked to aneuploidies and primary spontaneous recurrent abortions. Assessing the degree of aneuploidy and the genetic origin of foetal losses remains difficult to date, as examination of the miscarriage product is rarely available, due to the spontaneous nature of the loss.

An implantation failure (IF) is defined as the absence of pregnancy following the transfer of a good-quality embryo into the uterine cavity. These implantation failures can be due to embryonic factors, maternal factors, or caused by inappropriate stimulation and/or difficult transfers. In the literature, recurrent implantation failure (RIF) is defined as the absence of pregnancy after 3 attempts of transferring good-quality embryos, taking maternal age into account Setting up a prospective cohort of patients with RFC is an essential step in exploring the aetiological factors of RCF and in order to enable better treatment.