Endocrinology 14 - Contraception & Infertility Contraception - prevention of pregnancy before foetal implantation Abstinence - 100% reliable Block access of sperm to egg Disrupts the female reproductive cycle We can use the HPG axis to hormonally regulate fertility - By using exogenous hormones - There are number of different stages we can interfere in o Follicle stage " Prevent that primary follicle from developing in the ovaries o Prevent ovulation altogether . Oocyte not being released o After ovulation " Block degeneration of the corpus luteum . Blocking the cycle starting again · Blocking another ovulation o Unreceptive endometrium . Maintain the lining in an unreceptive state - All of these stages will be stopped if we stop the feedback loops in the HPG axis Hormonal Contraceptives: Combined oral contraceptives - Combined oestrogen and progesterone - Maintain sustained high levels of these two hormones o Hormonally mimics pregnancy - Pregnancy prevents the cycle from continuing - Oestrogen & progesterone will inhibit GnRH o And FSH and LH from anterior pituitary - High levels of progesterone will add an additional level of inhibition at the anterior pituitary - At the follicles; o maturation will be inhibited o we will not see ovulation . As there is no LSH o Inhibit corpus luteum generation - Will see changes in endometrium; Thickening of cervical mucous Prevent entry of sperm up the oviduct o Modify the ability of the oocyte . Can't move down the oviduct o Endometrial changes . Prevent the fertilised oocyte from embedding in the endometrium - Efficacy: o Very low failure rate (5 in 1000 - 0.05%)
o Usually caused by missed doses and drug interactions, diarrhoea and vomiting - Side Effects: o Increased risk of CVD, breast cancer, depres A lot of these side - Health Benefits: effects come from the oestrogen component of the pill so will switch to progesterone- only o Decreased risk of ovarian & endometrial can o Decreased incidence of PID & ovarian cysts Progesterone-only contraceptives - Mini pill o Can still get ovulation when taking these pills - need to be taken reliably o Supplies a low dose of progesterone o Inhibits anterior pituitary o The pituitary can still respond to signals from the hypothalamus . The hypothalamus still produces GnRH o Follicles; " Can still be ovulatiomn . Depends on the level of suppression of the HPG axis · Patient by patient o Endometrial changes " Thicken of cervical mucous . Modify the ability of the oocyte to move down the oviduct Supplying these hormones endogenous ly inhibits - Depo contraceptive injection o Higher dose of progesterone o Inhibits GnRH release, FSH, and LH o Follicle; . Inhibit follicle maturation Inhibit ovulation · Inhibit corpus luteum o Endometrium Thicken cervical mucous " Modify the ability of the oocyte to move down the oviduct - Efficacy: o Very low failure o Mini pill: must be taken daily - Side Effects; o Rare; acne, breast tenderness, mood changes o Depo injections - can take