I know social workers will always try to ensure that foster carers and adopters are able to understand the birthmothers of these children and feel some sort of empathy for them. Most people on the adoption threads know I have a 30 year career (now retired) as a social worker and team manager of a LA fostering & Adoption team. During the prep course we always did a session on birthparents and the importance of not running them down in any way in front of the children.
I have seen many sad cases of abused/neglected children and I can honestly say I have never known such a case where the parents have not been ill treated themselves as children, have mental health problems/learning difficulties and sometimes a combination of all three. That is NOT to say that people who suffered trauma in their childhood will all go on to inflict trauma in their own children. In fact many will ensure that their child doesn't suffer in the same way that they did.
The parents I have come across over the years are often young, almost always emotionally immature (a big gap between their emotional and chronological age) so children trying to parent children really, have no support from their own family, financial problems, poor housing, domestic violence in the home, complete lack of understand of the child's needs. Many young mothers feel that the baby will be someone to love them (as they have never really experienced this) and then when they find this isn't the case, they are confused and unable to cope and may ill treat the child.
There will be many other reasons, but these are just a few, but I believe that these birthparents whose children are removed and placed for adoption will be amongst the most disadvantaged and deprived sections of our society. Psychologically they can be seen as victims but sometimes victims turn into perpetrators and we see this in all sorts of ways, including physical ill treatment, neglect and sexual abuse. Many sexual abusers were victims of such abuse themselves and this incidentally is true (though to a much lesser extent) of women as well as men.
I got into deep water on MN once as an adopter described the birthmother as "pond life" and I'm afraid I reacted rather strongly. The adopter was furious and told me that I had no idea what she had done to her child, well I probably had, and many other things too, and yes it is a tough one, because we want adopters to love the children and not think badly of the parents who caused them such psychological harm, and it's ok for social workers as they don't have to cope with the harm that has been caused to the children. I was however disheartened that many other adopters piled in to support the issue BMs being "pond life"
SO I suppose it's a matter for your own conscience at the end of the day and whether you are someone who can feel empathy for people who have never really had much of a chance in life, or whether you feel that that doesn't mean they had to inflict such harm on their own child. I believe that in the main we parent our own children in the way that we were parented although there are exceptions as I have outlined above. These parents of children who are removed will only have one model of parenting, the one they received themselves and the really sad thing is that so many of them don't believe they had a hard childhood, saying things like "well my dad hit me with a belt and it never did me any harm............"