Sister did drugs until 18 weeks!!

Does anyone have experience with this?! Im freaking out, she is now on methadone and has been struggling with pain pills/snorting heroin since finding out she is pregnant. She says she cut down to only taking a pill or "small line" (ugh i know) when she had withdrawal symptoms. I have sent her endless information of what she could potentially be doing to my niece and am thankful shes now stopped and atleast on methadone. Can anyone tell me if her baby will be okay? What problems have babies actually been born with that were exposed to these drugs until now (18 weeks). Oh also i read that babies exposed to drugs are smaller and form slower than regular babies. Could my niece be older than 18weeks you think?! Ugh i just want to know if the baby will be okay. Someone, anyoneeee with experience please let me know and comment!! Id reallyyyy appreciate it!!