Yes, they will help you and yes your prospective employer will be notified. I went through the same thing with one of my employees and the company that did the health checks did contact us to let us know she didn't do the xray because there was a possibility she was pregnant.
Now a good and ethical employer shouldn't balk about that BUT reality being what it is, they might. (Although if they're paying you en blanco which it sounds like they are, the gov't actually pays your maternity leave directly so it's not an additional cost to the company). However, no company wants to think about the expense and time of hiring someone who is going to go out on maternity in 6 months and maybe not come back, etc.
If it were me, and I didn't know the company, I would probably go get a pregnancy test on my own time, prior to getting a chest xray. If it's negative, no harm and you can go do the xray. If it's positive, you will have the time to think about what you're going to say to your prospective employers. Do you have health insurance? I also don't know how that would impact your health insurance coverage if your employer is going to provide that (more than obra social).
The home pregnancy tests are like 99% accurate or you can do it with your gyn or walk in to a clinic or hospital and they can do a urine or blood test to confirm if you are pregnant or not.
