Combined Estrogen–progestogen Contraceptives

Combined hormonal contraceptives consist of an estrogen and a progestogen, and act primarily by preventing ovulation through the inhibition of the follicle-stimulating hormone and luteinizing hormone. The progestogen component also renders the cervical mucus relatively impenetrable to sperm, and reduces the receptivity of the endometrium to implantation (IARC, 2007). A variety of innovations have been developed since combined hormonal contraceptives were first available in the late 1950s, including changes in drug components, doses used, and the temporal sequencing of exposure to drugs. The dominant trends have been towards less androgenic progestogens, lower doses of estrogen and progestogen, the near abandonment of hormonal contraceptives with an estrogen-only phase, a proliferation of different product formulations, and continuing development of novel delivery systems (IARC, 2007). 1.1 Identification of the agents