The 3 Contraceptive Modalities

Systemic Progestins
-Combined Estradiol+Progesterone (pill, transderm patch, vag ring)
-Progesterone implant/injection
Mechanism: Suppress GnRH and by extension LH inhibiting ovulation, and FSH preventing the follicular phase (stroma/gland < 1:1) leading up to ovulation.

Locally-acting Progestins
-Progesterone-analog ONLY pill (norethindrone)
-Levonorgestrel IUD
Mechanism: Thicken cervical mucus, impair sperm penetration

Copper IUD
-chronic cytotoxic environment
-inflamm. response in uterus, impairing sperm migration.

Testing trick: IUDs proportionally increase ectopic/tubal pregnancies, but numerically decrease ectopic/tubal pregnancies.