I think this is something far off t be worrying about. You are so early in your nursing journey. You may or may not end up in L&D. You may have clinical in it and hate it. You may like it but discover something you like far more. There are so many other things. I deal with it the same way one deals with the many hard things we see. I, personally, treat them as I would any other patient. There are many hardships people face and it's not my job to judge them. Many people make mistakes, sometimes those are the people that may need the most help. Also you are not going to generally know who really does or doesn't use. Most people are not going to tell you they smoke, drink, or used illicit drugs. You aren't going to drug screen every pt. Things are just different when it's you and that patient one on one. You see them for a lot more which also makes it easier. Just because someone is pregnant and has a substance abuse problem doesn't make it any easier to get clean. Just try to keep an open mind and heart, do your best and it's not that hard.