How To Remove Drugs From Body During Pregnancy?

I am 6 weeks and 3 days pregnant just found out 3 days ago I have a drug test Tuesday and if I fail I go to jail usually I would use niacin to clean my system but now that I m pregnant I can not do that. I am fully done smoking weed for the rest of my life it s a wake up call to me. But I can not go to jail pregnant and as sick as I have been. Last time I smoked was Tuesday of last week. Is there any way I can clean my system without harming my baby. ?