Combined hormonal contraception
Menstrual cycle regulation by hormonal pathways1,2
- Hypothalamus releases GnRH, stimulating the pituitary
- FSH slowly increases causing LH surge that stimulates ovulation
- Estrogen and progesterone provide negative feedback to the hypothalamus and pituitary, turning off GnRH, LH and FSH release
GnRH = gonadotropin releasing hormone ; FSH = follicle-stimulating hormone; LH = luteinizing hormone Used with permission from The Journal of Reproduction Medicine.
1Speroff L and Fritz MA. Regulation of the Menstrual Cycle. In: Clinical Gynecologic Endocrinology and Infertility; Philadelphia: Lippincott Williams & Wilkins, 2005
2Griesinger G et al. J Reprod Med. 2011;56:279-300
Combined oral contraceptive pills: mechanisms of action
Progestin: imitates progesterone increase in pregnancy
- Inhibits ovulation by suppressing FSH and LH
- Thickens the cervical mucus thereby preventing the migration of sperm into the uterus
- Alters the endometrium, making it unsuitable for implantation even if the ovum is fertilized
Helps to maintain the stability of the endometrium and thereby decreases the risk of break-through bleedings
Speroff L. Oral contraception. In: Clinical Gynecologic Endocrinology and Infertility; Philadelphia:Lippincott Williams & Wilkins, 2005:861-942.
Thus Progesterone provides the Contraceptive Effect And Estrogen regulates the Bleeding Pattern
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