Expressions of steroid receptors and Ki67 in first-trimester decidua and chorionic villi exposed to levonorgestrel used for emergency contraception

Levonorgestrel (1.5 mg) is commonly used for emergency contraception to prevent an unwanted pregnancy after an unprotected intercourse. We found that postovulatory administration of 1.5 mg of levonorgestrel to women with a subsequent or existing early pregnancy did not affect the immunohistochemical expressions of estrogen receptors (ERα, ERβ), P receptors (PRB, PRA+B), androgen receptor (AR), or proliferation index Ki67 in the first-trimester decidua and chorionic villi.