ICOS and spontaneous abortion: In accordance with the suggestion that increased numbers of CD4+ FHM cells may be implicated in pregnancy loss, a human study in recurrent miscarriage found higher decidual CD4+ FHM cells (CXCR5+PD-1+CCR7− and CXCR5+PD-1+ICOS+) in spontaneous miscarriage decidual tissue compared to tissue from elective terminations in healthy women (43).