I just wanted to ask,I am having a blood test in a month and wanted to know if you get a blood test on your wrist,can the doctor tell if you have started your period with your blood? thank you very much ,
Its not me that is having the blood test my cousin up in london wanted to know

It depends on what they use your blood for. If they test iron levels, they might see a decrease, which is a CLUE that the woman has been recently or is on her period.
I'm not sure why that should matter to you though.

What blood tests can you tell in?