Excellent advice from sweet chili
Don't rely on SW assessment of the child in terms on development, future risks etc. They are not HCP and dont know a lot about this area. They are also motivated by the desire to get children placed asap so tend to be optimistic to say the least.
Also if baby is newborn , there's a limit to what anyone can tell you. Trying to do a risk assessment is very hard .
E.g. You say BM used heroin and other drugs. No one can know how much and how often and at what stage of the baby's development. She undoubtedly used alcohol as well, which is very risky for baby.
Im sure you will understand that there's very little hard evidence on the effects of poly drug use pre natally. Users don't know what they took and when, even if they wanted to tell you. They don't know the contents of what they take if they are buying it on the streets.
One BM might be in prison for the early stages of pregnancy , so her drug use will be much less, as anything she has taken inside will be very weak. So perhaps her baby will suffer less damage - who knows ?
Another will be using a range of drugs all the way though. A third may only drink heavily and her baby might be affected even more.
All three women will be classed as drug users who lose their babies . All three Babies may not be affected to the same extent.
So you can ask questions about the background , but I doubt if you will be able to tell much about the risk to the baby from drugs etc. And that's not counting the influence of cortisol ( which we know about ) and the genetic issues from mental health problems .
So no one can give you any real assessment of how likely it is that baby will suffer long term problems. The only way to know is it wait until the child is much older - most soft brain damage will have shown up by the age of 7 or so. But understandably most adopters aren't willing to wait to adopt an 7yo.
FWIW I know two foster carers who had babies placed at birth from similar backgrounds in the last two years,
All FC were very good, had grown up kids of their own and both foster mothers have professional childcare experience. Both babies got the very best of care from the moment they were born. Both had significant delays when they were finally placed for adoption at about 12-15 months.
So you need to know that love and attention doesn't fix everything. If you go ahead you need to accept that there's a significant risk that this baby may have long term needs.
Only you know if you can take that risk. I'm so sorry, I know it's really really hard.