Mechanistically, EA intervention significantly improved the number of blastocyst implantation and pregnancy rate in PCOS rats by up-regulating the mRNA and protein expressions of insulin receptor substrate 1 (IRS1) and insulin receptor substrate 2 (IRS2) in the endometrium (Lai et al., 2016a; Lai et al., 2016b). Here, IRS1 is linked to polycystic ovary syndrome.