Baby born addicted to meth

So I know absolutely nothing about drugs so I have a few questions. My cousin had her baby 2 days ago and he tested positive for meth, unfortunately. Her and the babies dad are now in jail thank goodness but why would they test the baby in the first place? Do they test every baby? My cousins excuse is that she did it before she found out she was pregnant which would be about 4 months ago. Is she lying or would the test actually pick up on it from that long ago? And last thing, does anyone know what symptoms the poor baby might have now? He is weezing really bad and sneezing blood so I don't know if that has anything to do with it. He wasn't born premature and he weighed 7 lbs 10 oz.