It's normal for women to miss their periods when on birth control, regardless of brand or type, according to Planned Parenthood of Maryland. Switching types or brands is a common cause of missed periods.
Taking a birth control pill once a day, every day, creates 99 percent effective protection against pregnancy. If a woman is taking her pill daily without missing or skipping doses, it is very unlikely that she is pregnant. She may be experiencing secondary-amenorrhea, a medical condition in which a woman doesn't menstruate for six months or more. Switching birth control methods or brands is a common cause for missed periods, especially if the pill contains progesterone, according to the Palo Alto Medical Foundation.