Yes, they probably could.

Is there a specific reason you need to know?

No. Those hormones are found in your body naturally, so no test will be able to detect them (or at least they won't be able to tell if they're higher than normal).

If you are testing for something then its important to tell your doctor because birth control pills can affect some blood tests (sorry for not elaborating my thoughts).

Since I don't know this situation, I'll just add that even if you are a teen, your doctor cannot tell your parents you are taking birth control pills.

Thank you for your replies, but I'm still wondering if they can or not.

I would like to know because I am 19 and while my parents may not agree with me TTC, I am interested in it for the near future. They pay for my birth control pills, and my mom comes with me to my gyno appts so everything would be said in front of her if there was anything to be said.

I still don't see why they would be testing for birth control pills? I suppose you could easily lie and say you were taking them, but that would be incredibly underhanded and pretty juvenile.

You might want to wait to have a baby if you're still, for the most part, relying on your parents for things like appointments and insurance.

If nothing else, talk it over with your mom upfront rather than lying about taking pills that she's putting money into for you benefit.