Knowing when to switch birth control pills can be fairly obvious for some women. Other women may not realize the effect her pills are having on her and continue taking them. Annual appointments with a health-care professional are important in helping a woman identify potential reasons to change birth control pills.

Progesterone, one of the most important hormones for pregnancy and for regulating menstrual periods, is normally found in synthetic form in birth control pills. Some alternative practitioners advocate taking natural progesterone in addition to birth control pills to counteract some of the common side effects.

Sometimes your period falls at an inconvenient time in your life, and it may become necessary to stop your period for a few days. According to Dr. Rosalinda Abboud, a gynecologist at the Mayo Clinic in Rochester, Minnesota, no side effects come with stopping or delaying your period.

Scientific studies indicate that hormonal birth control doesn't directly cause weight gain, according to MayoClinic.com. Still, many women who use it do gain weight -- particularly in their hips, thighs and breasts.