I don't know this case but I do have experience of SS becoming involved due to MH in pregnancy.
I am fairly educated, speak with a middle class accent (or so I have been told -whatever that is) and yet was in the care system myself and as such had developed significant MH problems that came to a head during my pregnancy
My experience was I did come across one gun ho SW who was ready to have my baby taken unless I jumped through x number of hoops... (which she discovered I was already jumping through off my own back proactively trying to make sure I did my best for my kid e.g. Therapy, support groups, specialist midwife etc)
Then I gave birth and was fortunate enough to be in an MBU for a time which probably saved me losing my baby
I had a lovely SW then who definitely was never considering removing the child and closed the case quite quickly
What both gun ho and lovely SW and tons of support agencies and midwives missed - was that I was in an abusive relationship with a very clever manipulative man and he was having a huge impact on my MH and has now affected my child badly in the years it took me to wake up and get out. I was very good at hiding the abuse and blaming my own MH, he was very good at blaming my MH too!
Along the way I've met many women who've been through things like me... and honestly I can say I do see a difference in terms of the treatment of those who appear better spoken, those who you can automatically tell have had a difficult childhood themselves from the moment they speak
I'm obviously super glad I haven't lost my child and we're okay now. I do think back though and think if only you had really known everything or I spoke less well... would you still have let me be a mother or taken my kid away?
Ironically the "support" bwahahaha, yeah right! I got from abusive man which was a lovely front to all and sundry was one of their "protective factors" so I was trapped into staying with him for a while even if I had have woken up to the fact it's not normal to have to control your baby's every movement so as not to "stress out" some dick, or other stupidity I now can't believe I ever put up with (like pushing me around in front of my kid as long as he never left a bruise I could ever show to anyone)
No, they don't always get it right.