The Vall d'Hebron Research Institute (VHIR) has signed an agreement with the international human assisted reproduction center of Barcelona (CIRHAB-GRáVIDA). The agreement consists of an economic grant of 45,000 euros / year for a minimum of 3 years of the entity CIRHAB-GRáVIDA to collaborate in the research developed by Dr. Jaume Alijotas Reig, senior consultant at the Internal Medicine Department of Vall d'Hebron University Hospital, Professor of the Department of Medicine of the Autonomous University of Barcelona (UAB) and head of the VHIR Systemic Disease Research group.Only 30% of all embryos of healthy women end with a pregnancy, although the objective abortion rate is 15%. In addition, 3-5% of women of childbearing age have recurrent abortions, Therefore, human reproduction can be considered as a process of low efficiency. Most of these cases are without diagnosis once the most common causes have been excluded.In recent years it has been observed that these types of complications can be related to immunological disorders. These alterations can be autoimmune, meaning that antibodies recognize their own molecules as strange and cause self-aggression. Or, aloimmune, the maternal immune system rejects the embryo.That is why pregnancy should be understood as a great immune challenge where the mother must generate tolerance in front of the embryo antigens that can be different from their own. If this tolerance does not exist, the immune rejection mediated essentially by T cells occurs and this makes the correct development of pregnancy impossible.This research scholarship aims to study and deepen the knowledge of the antibodies that are believed to cause trophoblast injury and / or placental vessels, as well as molecules that can favor maternal tolerance against fetal antígens from the father. The research group of Dr. Alijotas-Reig is confident that with this immune study he will be able to explore this problem and find a new biomarker that will allow to optimize and customize the treatment and to enable the study of new therapeutic pathways.