by Amber Hilton

Created on: July 22, 2010

The birth control shot, marketed under the brand name Depo Provera, is one of several reversible, hormonal prescription birth control methods available to women. As with any form of hormonal birth control, there are pros and cons of taking Depo Provera. Pros of the birth control shot include pregnancy protection and decreased periods; many women also prefer this method because they don't have to remember to take a pill every day, which cuts down on user error. Cons include health risks and side effects, such as spotting and weight gain. If you're considering this type of hormonal birth control, you might be wondering, "How does the birth control shot work?"

Depo Provera works by releasing a synthetic version of the hormone progesterone slowly into your body over the course of 11-14 weeks. Women who rely on the birth control shot for pregnancy prevention must visit their doctor approximately every 12 weeks (every three months or approximately four times per year) for an injection.

The progesterone in the birth control shot prevents pregnancy in at least three ways. For starters, the synthetic hormone in the birth control shot prevents ovulation from taking place, so there is no possibility of sperm fertilizing an egg. The hormone also thickens a woman's cervical mucus, which hinders a sperm's ability to swim into the uterus. Finally, Depo Provera may also prevent uterine tissue from building each month, which accounts for the fact that many women have decreased periods while taking the birth control shot. Without a thick uterine lining, it becomes difficult for an egg to implant in the uterine wall, although the shot should prevent an egg from being released or fertilized in the first place.

If a woman misses a shot or goes too long in between shots, her chances of an unplanned pregnancy greatly increase. Many women prefer this method of birth control, considering it more convenient and effective than oral contraceptives, which require them to remember to take a pill at the same time each day in order to be effective. Although spotting or continuous bleeding are common side effects while your body adjusts to the hormones in the birth control shot, by month six, a third of all women report a complete cessation of their monthly period, known as amenorrhea. After a year on the shot, more than half of women report that their periods have stopped completely. For many women, this is another huge benefit of the birth control shot.

If you're unhappy with your current form of hormonal birth control and are looking for a method that is easy and effective, you might consider the birth control shot. This method is also a viable solution for women who would like to have decreased periods and have experienced unwanted spotting with seasonal oral contraceptive methods, such as Seasonique or Seasonale.

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