Black tar? What are you talking about?
Honey, I can see you are anxious for an answer, but there is so much to this issue that it's hard to know where to begin. For one, most pregnant women would not take anything without discussing it with their doctor. Yet you say her mother is giving her codeine on the side? For another, it sounds like she is more concerned with getting caught than being healthy for the baby ... even if she stops, will she be going back onto unprescribed codeine when the baby is born? For another, there is an assumption that the baby is going to be drug tested ... is that a well founded fear, in other words, is she being watched already for using drugs that she is not supposed to be using? I really wonder if you should not just urge her to discuss the painkiller use with her doctor right away, so it is in her record and she won't be in a position to have to lie about it. A doctor can help someone who is dependent on a drug, to kick it.