Is it actually a good idea for her to have a baby?
It doesn't sound like it does it? Not on any level. However, there is fuck all any of us can do about that. The OP has said a termination isn't going to happen and if this girl wants a baby she will be told it's her right to have a baby. How she will support it financially, emotionally, practically is clearly neither here nor there, so we just have to hope that there are enough supportive people around her to regularly monitor things and make sure that the child doesn't grow up in a completely dysfunctional and inadequate environment.
I remember reading a thread where an autistic woman glibly described some of the things that passed for normal in her house in regard to her autism and how it affected her parenting and honestly, I was horrified. Those poor kids don't stand a chance. I only hope someone else in their lives is working to plug the gaps in their emotional development that are being caused by their mother's inability to cope. Such as a dislike of having them want to touch her.... and regular meltdowns in front of the children where her partner knows that he needs to 'pick her up and carry her' to another room so she can calm down on her own. This is the mother we are talking about, not some hangry two year old. Seriously. Can you imagine young children growing up with this?
Given the sheer scale of young people roughly this age and younger who identify as autistic, ADHD, highly anxious or depressed, too physically weak to stand up for long, have poor concentration spans, an inability to organise themselves and are pretty much unemployable due to all of the above, we can expect to see a whole new generation of children born into some very challenging situations indeed in the next ten years or so.
If teachers think they have it hard now with huge numbers of children arriving at school not potty trained at four and not able to sit still and listen for 2 minutes and having violent outbursts at 5 and 6 years old, just wait until those children start having children. We are fucked.