↑ Rivera R, Yacobson I, Grimes D (1999). “The mechanism of action of hormonal contraceptives and intrauterine contraceptive devices”. Am J Obstet Gynecol. 181 (5 Pt 1): 1263–9. doi:10.1016/S0002-9378(99)70120-1. PMID10561657. The hormonal methods, particularly the low-dose progestin-only products and emergency contraceptive pills, have effects on the endometrium that, theoretically, could affect implantation. However, no scientific evidence indicates that prevention of implantation actually results from the use of these methods.
↑ Phelps, Rachel (tháng 6 năm 2014). “Choosing a Birth Control Method”. Association of Reproductive Health Professionals. Bayer Healthcare Pharmaceuticals, Conceptus, Inc., and Teva Pharmaceuticals. Bản gốc lưu trữ ngày 2 tháng 1 năm 2018. Truy cập ngày 16 tháng 9 năm 2016.
