Can you get pregnant when you are on the pill and if you do is it harmful to the baby if I didn't know and still took the pills??

Its possible to get pregnant on the pill (I did).
I don't believe there is substantial evidence to prove taking the pill would hurt a fetus. It is advised you stop as soon as your suspect pregnancy though.

Two of my friends got pregnant while taking the pill religiously. Ask your doctor for a pregnancy test if you suspect you might be. As long as you stop as soon as you suspect, you should be OK, but mention that to the doctor too. Good luck!

I conceived my daughter while on the pill. I took it everyday and the same time, and never missed one. In fact, when I started having morning sickness I thought I had food poisoning from Taco Bell! HAHA When I went to my doctor about it, I also complained of side pain (another sign of pregnancy)... he asked could I be pregnant and I said no, because I was on the pill. He thought I may have had appendicitis... until the bloodwork came back... SURPRISE!

So yes, you can get pregnant on the pill... at best, it is only about 97% effective.

There is no real danger if you continued to take the pills without knowing. I was still taking my pills and I was 4 weeks pregnant, my daughter was absolutely perfect :)

Yes, the pill is not 100 percent effective, and if you miss one, the odds go up greatly. This is something people forget, you should be OK, but if you believe you are, be tested

Many people have gotten pregnant while on the pill. I've never herd of any side effects towards the baby.
If you are concerned about becoming pregnant when you are on the pill you should think about a second form of birth control like a condom.