Hormonal contraception

Mechanism of action for hormonal contraceptives

• Estrogen: suppresses release of GnRH from the hypothalamus → ↓ release of pituitary gonadotropins (FSH, LH)
  • Decreased FSH → prevents ovarian folliculogenesis
  • Decreased LH → inhibition of ovulation
• Progestin: synthetic progesterone →
  • Inhibits GnRH and LH secretion → suppressed ovulation (main contraceptive mechanism)
  • Inhibits endometrial proliferation → decreases chance of embryo implantation
  • Changes cervical mucus (↓ volume and ↑ viscosity) and impairs fallopian tube peristalsis → inhibits sperm migration and embryo implantation