LIF is a cytokine that is essential for the development of the central nervous system, and has recently been shown in rats that maternal LIF stimulates placental ACTH (adrenocorticotropic hormone) that in turn promotes secretion of fetal LIF from nRBC (nucleated red blood cell ), which in turn promotes brain development of the fetus In other studies on rats a theory was proposed that LPS (lipopolysaccharide) and infection during pregnancy influence the normal development of the brain and may cause brain damage by altering placental ACTH thank in turn alters LIF secretion in the embryo which could be the cause of brain damage.