Women confronted with recurrent pregnancy loss (RPL) are often desperately searching for a possible explanation and hoping they will someday fulfill a healthy pregnancy. Unfortunately, in more than 50% of these women no cause for their losses can be identified after clinical investigations and therefore clinicians have no treatment options to help these women. Although adaptations in several systems such as the metabolic, the cardiovascular, and the immune system are highly important to support early pregnancy, especially the contribution of a specific subset of immune cells in the uterus known as CD56