I have recently started the depo about a month ago and I know that its impossible to start your period on it unless your pregnant. I was wondering if this is true?:confused:

Well, I took it for 2 years and never, not once, had a period.

But you should also know that just because you do not have a period does not necessarily mean you do not ovulate.

No birth control of any kind is 100% effective. The only 100% effective form of birth control is abstinence.

Yes it is true. It is not a definite 100% but about 85%

For the first month you should be using another form of birth control along with the shot to prevent pregnancy. Where you received your shot should have counsled you about this. You should really call the doctor/clinic you received your depo shot from and talk to them. They will most likely have you come in for a pregnancy test. Let us know how things go for you. I hope everything works out for you.