Contraception Hormonal Methods The Shot

Birth control shots (such as the Depo Provera® shot) contain progestin, a synthetic hormone that acts the same way as the natural hormone progesterone. When progestin is injected into the arm, the shot works to prevent pregnancy. Unlike other types of contraceptives, the Depo shot doesn’t contain estrogen, making it safe for women who are breastfeeding.

To work effectively, the shot should be injected every three months, seven days after the end of your last period.

How Does Depo Birth Control Work?

The Depo shot stops the ovaries from releasing an egg in addition to thickening the mucous that lines the cervix. These two things combined make it highly improbable for sperm to enter into the uterine cavity, fertilize the egg, and also implant into the endometrial cavity. In addition, the Depo Provera® shot also creates a thinner uterus, which is believed to help prevent pregnancy.

Benefits, Side Effects and Drawbacks of the Depo Shot

As with any other form of birth control, there are certain benefits and risks that should be carefully considered prior to using Depo Provera®. Speak with your doctor about the following benefits and risks of the shot.

Benefits of depo birth control include:

  • It does not contain estrogen
  • It’s highly effective
  • You don’t need to take a daily pill or use another form of contraception (aside from condoms, if you’re worried about STDs).

Drawbacks of the depo shot include:

  • Delayed pregnancy (In some instances, it takes more than one year to become pregnant after using a birth control shot.)
  • Periods may become lighter or heavier, depending upon the individual.
  • The possibility of spotting and bleeding in-between periods.

Some women also experience unpleasant side effects when using the shot as a contraceptive, including:

  • Depression
  • Nausea
  • Reduced sex drive
  • Weight gain.

Are Depo Provera® Shots Effective?

The shot doesn’t prevent sexually transmitted diseases. However, the depo shot is highly effective in most cases. Here are the facts concerning the effectiveness of Depo Provera® shots:

  • 1 out of every 100 women will become pregnant when taking the depo shot every 12 weeks.
  • 3 out of every 100 women will become pregnant when taking the shot irregularly.
  • If a Depo Provera® shot isn’t administered on time, you won’t be protected right away, and you’ll need other forms of birth control during the first week.

Is Depo Birth Control Right for Me?

The shot isn’t right for everyone. Women with the following conditions shouldn’t take the shot, and may want to consider other forms of contraception:

  • Blood clots
  • Cancer
  • Depression
  • Gall bladder disease
  • Liver disease.

The best way to determine whether or not Depo Provera® is right for you is to speak with your doctor.


Kid’s Health Staff. (2009). Contraception: Depo shot. Retrieved February 11, 2010, from the Kid’s Health Web site:

Planned Parenthood Staff. (2010). Birth control shot: Depo provera®. Retrieved February 10, 2010, from the Planned Parenthood Web site:

Women’s Health Staff. (n.d.). Depo shot. Retrieved February 10, 2010, from the Women’s Health UK Web site: