LIF and adenomyosis: Several studies support that in infertile women with adenomyosis, long-acting GnRH agonist protocol achieved better pregnancy outcomes after fresh embryo transfer [9, 10], with potential underlying mechanism, such as decreased expression of cytochrome P450 in adenomyosis lesions [11], down-regulation of circulating estrogen levels by inhibiting hypothalamic-pituitary axis, improved microenvironment and follicular quality [12], and ameliorative endometrial receptivity by up-regulating Hoxa10, Hoxa11, Lif and integrinβ3 [13].