The immune system has been established as one of the major regulators in the process of embryo implantation and in the subsequent maintenance of pregnancy.

Uterine Natural killer cells, except being an important component of the local maternal immune response to pathogens, may play a significant role in the early stages of the embryo implantation process (trophoblastic invasion and angiogenesis).

There are encouraging results which suggest that the infusion of 20% intravenous fat emulsion (which consists of natural ingredients) can modulate the immune system response by decreasing NK cells cytotoxic activity which has been related to recurrent implantation failures and therefore enhance fertility treatment outcome