Summary: The Depo Provera shot is a very popular and convenient method of birth control. However, because it is long-acting some women have difficulty getting pregnant after stopping it. One large study and patient feedback shows that the time to conception can vary wildly from woman to woman.
Dear Curtis: I was on the Depo-Provera shot for just over 3 years. My husband and I have decided that we would like to start trying to get pregnant. My last shot was two months ago. How long do you think it will take for the Depo to wear off?
It’s a fairly common concern among women. First and foremost, a lot of women get the Depo-Provera® shot (medroxyprogesterone) because it is so effective at preventing pregnancy. But, because it’s long acting (one shot every thirteen weeks) the effects can carry on longer. And generally speaking, women do have a more difficult time getting pregnanat after stopping Depo vs. stopping the birth control pill.
I obviously can’t give you an exact answer. I can give you best case scenario and time frames that other women have experienced.
Depo’s Half Life In Your Body
First of all, Depo Provera can be administered in two different ways: IM (Intramuscular – a ‘deep’ shot that is given in your buttock or shoulder) or SQ (Subcutaneous – a short-needle shot given in thigh or abdomen). According to the manufacturer it which shot you are given when it comes to how long the shot lasts in your body. In short, it doesn’t matter which shot you were given.
Now, when Depo is injected into your body it actually has a very long ‘half-life’ and stays in your system for quite a while. This is the main reason why you only have to get an injection (IM) every 13 weeks or every 12 to 14 weeks for the SQ injection. I’ve written about this before but pharmacists use the half-life of a drug as a reliable indicator to determine when a drug will, for practical purposes, be out of your body.
Most pharmacists will use four to five half-lives to determine when the drug is gone. In the case of Depo Provera the half life is 50 days. So, multiplying out by four to five you get 200 to 250 days before the Depo is out of your system enough and you can expect to increase your chances of becoming pregnant.
What Studies Show Us
There have been studies looking at the return of fertility following Depo usage. What they found seems to support the half life calculation.
- Roughly 50% of women who become pregnant after using medroxyprogesterone injection do so in about 10 months after their last injection.
- Roughly 67% become pregnant in about 12 months
- About 83% become pregnant within 15 months
- And 93% become pregnant within 18 months of their last injection.
One thing we also know from the studies is that a woman’s weight has no effect on how long it takes you to become pregnant.
Your Personal Situation
Right now you said you are two months out from your last injection. So, that’s about 60 days. Using our calculation above and the available study I would expect you to not have any success achieving pregnancy for at least another 4 months and probably closer to five months. By month eight or nine (starting from day of last injection) the Depo should be out of your system completely.
If you are seriously committed to getting pregnant and the earliest possible time I would recommend using a fertility monitor (again, starting at about day 200).
Let me also say that you can become pregnant sooner. In fact, some women become pregnant who are diligently taking the Depo shot. However, it’s very rare and I wouldn’t count on it. But I mention it because it is a possibility.