i want to know because i'm going to the doctor tomorrow and i'm going to the doctor for blood tests to see why my period is irregular. my mother is not aware that i'm sexually active and i'm scared she will find out.
you can not tell by blood and urine tests, unless you have contracted a sexually transmitted disease. you can however sometimes tell by pelvic exam. legally though this can not be discussed with your mother without your permission even if you are a minor. no worries.
It is difficult to tell from your blood or urine sample. However, if they have to do an examination of your "private parts", then they can tell. Be prepare because they may have to do this if they cannot see anything wrong with your samples.
They can't tell through a urine test, but if they are going to be doing a papsmear then they will be able to tell. If you are "legal" then you can choose for it to be confidential and they legally can't tell your mother. You should tell her anyways and ask to get put on birth control. I would rather my daughter told me so we could prevent pregnancy at an early age so she doesn't make my mistakes.
depending on your state, your Dr. has to get your permission to tell your mom anything. Just tell your mom to wait in the waiting room because you want to talk to the Dr. alone.