Hello Thank you for trusting Healthcare Magic Dear barrier contraceptive methods are best than I-pill high dose of progesterone. It may be due to its side effect, the hormones in the pills (either progestin alone or progestin combined with estrogen) can cause some women to bleed at unexpected times. If that is the cause of your bleeding, it is not dangerous and you should expect it to go away by itself after you get your next period. May be breastfeeding prevent getting cycle for up to one year, but if your formula feeding means it may induce cycle with in 2-6weeks. I think I answered to your question if you have more questions feel free to ask. Take care