Hi, I had a sex with my girl friend 2nd march 2013, I used condom properly. And I checked all the condoms. Now she missed the period date by two days, can you please suggest me what could be the reason, is there any change of pregnancy?

There is no form of birth control that is 100% reliable. Condoms are the least reliable form, other than the pull out method which shouldn't even be on the list of birth control methods.

In other words, yes, she could be pregnant, even if you used the condom properly and checked them. There are women on this site and all over the world, that used 2 or more methods of birth control, all used correctly, and still became pregnant. It's not rare.

At two days late it's too early to test. She'll have to wait until her period is at least two weeks late, then test using first morning urine. If that test is negative then wait until her next period is due. If that period is missed, test again or get a blood test.

Bottom line, if you're having sex, you're ready to be a parent. If you're not ready to be a parent, you shouldn't be having sex.