I think too, many assume (and get caught up in the no judging of mums aspect of it) that there are only a few mums that drink heavily while pregnant, to the point of being drunk, with no regard to the baby. I've seen it in distant relatives of my partners family, women 6 months + pregnant downing beers, drunk and disorderly. They know it's wrong and they do it anyway and I've seen the problems their children have. I don't know exactly what the research shows but I'd assume that it's this level of drinking that produces worse results, than a mum who occasionally has a few glasses of wine with dinner.
There is so much education out there, it's common sense to not get drunk when you are pregnant but there will always be women who will do it and the kids have to live with the consequences. I've seen it first hand and it's bloody heartbreaking.