Can you get pregnant while on depo ?

A friend of mine thinks she's pregnant. She asked me if she could still get pregnant if she's on Depo - The birth control shot. She says she goes back to the doctor the 23rd of this month (February) to get the next shot.

I didn't know what to tell...

her, I only told her no birth control is 100% unless you just don't have sex.

Can you still get pregnant while on Depo?
and
Could the Depo cause harm?

It is unusual to get pregnant while taking Depo-Provera regularly, but pregnancies sometimes occur before the shot is given, and then go unrecognized until there is an obvious sign, like fetal movement. If a woman does becomes pregnant while using Depo Provera, and continues her pregnancy, there may be an increased risk of premature birth. Pregnancy and Depo Provera are like sunshine and rain. There is an extremely rare chance of them being together. Famed as one of the best birth control pills, Depo Provera is also infamous for preventing pregnancies even after use. This can be blamed on the long term effects of the hormone progestin, which is the main ingredient of Depo Provera.
- http://www.babyhopes.com/articles/depoprovera.html

Just like any other birth control - none of them are 100 percent effective. If she was having unprotected sex - there is always a chance she could be pregnant. I got pregnant while I was on birth control also.

If she is concerned that she is pregnant - she can get a pregnancy test and find out for sure.

From what I read, Yes, the only protection that's 100% guaranteed is not having sex. It is possible to get pregnant with any other form of birth control. If you think you are pregnant, go see a doctor or take a home test. Do not get your next shot until you are sure you're not pregnant.

hi please is it true that you can get pregnant on this depo shot because I had sex a few days ago and im ready for my shot monday 7th september 09 I have been get stomach ache for a few days after sex could I be pregnant please give me sum advice