What's the difference between -

I hadn't told you this, but I had gotten pregnant and

I haven't told you this, but I have gotten pregnant.

I know one is past perfect and the other is present perfect but don't they basically mean the same thing?

Thanks in advance.
The first certainly implies you are no longer pregnant.

The second says you are still pregnant.

I agree with Vic: I'm pregnant is the better choice over present perfect in this case.
"I hadn't told you this but I had gotten pregnant"= I got pregnant but didn't tell you

"I haven't told you this, but i have gotten pregnant." = I am pregnant is the result now... i would say " I haven't told you this, but I'm pregnant." I am telling you the news (information you don't know)
 BarbaraPA's reply was promoted to an answer.