It is possible to experience both normal and unusual vaginal bleeding while on birth control, WebMD states. This may include early periods, shorter periods, reduced flow, and spotting in between periods.
A woman on birth control may experience two varieties of vaginal bleeding: menstrual bleeding and spotting, according to WebMD. With traditional birth control, a woman takes active pills for a certain number of days, with 21 days being the norm, and then inactive (or placebo) pills for a certain number of days. It is during the week when taking the placebo pills that a woman experiences her period.
A woman may also experience spotting in between periods, notes WebMD. Some causes of spotting include hormonal imbalances and missed doses of birth control pills. If one is concerned about whether vaginal bleeding is normal, it is recommended to consult with a physician.