How Long Does Weed Stay In Pregnant Womans System? I

How long does weed stay in pregnant womans system? I smoke for pain and so I can eat. As I've gone Weeks without being able to hold anything on my stomach. And have lost a lot of weight due to not being able to eat. I live in TN and it's not legal here yet. Also I heard they drug test all newborns and mothers. If the baby or mother tests positive they will take away baby and mom goes to jail. So I'm kinda worried as I don't want to lose my child nor go to jail. However no medications are helping me except weed. As my Dr has also tried several medications with me such as zofran. I just want to have a healthy child and don't see how that's possible if she's not getting things she needs such as food.