Wisconsin drug testing

I know I'm going to get a ton of negative comments, to which I say keep to yourself. 
I am not proud of the fact I've been using marijuana to control my hypermesis..but I wasn't willing to take things that have been proven to potentially harm my baby. I've know people who haven't had the best outcomes with what a dr has prescribed..so this is what I chose instead. I was told by the hospital that they test all newborns for drugs..is that true? I have no idea how I'm going to eat now, because I am going to stop no matter what...but does anyone know if that's true? How do they test?