IGF1 and Infertility: A previous study reported that decreased lncRNA H19 expression increases miRNA let-7 activity by acting as a molecular sponge and then reduces the proliferation of endometrial stromal cells via insulin-like growth factor (IGF) signaling in eutopic endometrium of women with endometriosis, which may contribute to impaired endometrial receptivity for implantation and is associated with infertility (26).