So is irregular menstrual cycle, which birth control pills regulate. So what's your point?
Is that the main reason why women take birth control? Also, does viagra and penis pumps increase stroke risk cause cancer etc?
Birth-control pills reduce some kind of cancers, but increase others:
* A number of studies suggest that current use of oral contraceptives (birth control pills) appears to slightly increase the risk of breast cancer, especially among younger women. However, the risk level goes back to normal 10 years or more after discontinuing oral contraceptive use.
* Women who use oral contraceptives have reduced risks of ovarian and endometrial cancer. This protective effect increases with the length of time oral contraceptives are used.
* Oral contraceptive use is associated with an increased risk of cervical cancer; however, this increased risk may be because sexually active women have a higher risk of becoming infected with human papillomavirus, which causes virtually all cervical cancers.
* Women who take oral contraceptives have an increased risk of benign liver tumors, but the relationship between oral contraceptive use and malignant liver tumors is less clear.
Oral Contraceptives and Cancer Risk - National Cancer Institute