Hi, and thanks for your medical question on eHealth forum!
Breakthrough bleeding occurs due to hormonal fluctuations. One way to avoid this is to take the pills at same time everyday. Do not smoke. Drink alcohol sparingly. Switching to a monophasic or progesterone only pill decreases chances of breakthrough bleeding. Take Vit C supplement for sometime to increase pillâs absorption. Eat healthy. Consult your gynecologist. Hope this helps. Take care!