Estrogen + progestin suppress the hypothalamic-pituitary axis (↓ FSH/LH) → no LH surge → ovulation inhibited; progestin also thickens cervical mucus and thins the endometrium.
Black Box Warning
Cigarette smoking increases the risk of serious cardiovascular events from combined oral contraceptives; the risk rises with age (especially over 35) and with the number of cigarettes smoked — contraindicated in women over 35 who smoke.
Clinical Notes
Also treats menorrhagia, acne, and PCOS. Contraindicated in migraine with aura, prior VTE, and smokers >35 (↑ stroke/VTE/MI); guidelines (US MEC) treat ≥15 cigarettes/day over 35 as an absolute contraindication. The most-tested reproductive pharm.