If you knew someone who's dad had just died of lung cancer, and they announced it on FB, and there were 37 "Condolences" replies, you wouldn't become incensed with rage at the fact that he was a smoker so why should we feel sorry for him.
But any other day of the week, you might find yourself saying something like "The NHS has to deal with great financial strain when people come in with self-inflicted illnesses" (not my personal view, btw).
There is a time and a place to dispute something you disagree with, and in a comment responding to her announcing a big, scary and exciting change in her life would not be that time, so those 37 responses which have annoyed you so much are actually just polite, caring, supportive people. This woman's circumstances may not be ideal, but you appear to have been outraged by the fact that people have congratulated her, thereby "validating" her choices and mistakes, or society's choices and mistakes.
Any other day of the week, be annoyed at how the government is allowing the benefits-culture to spiral out of control etc, but there's a time and a place and a woman making the brave and frightening decision to become a single parent isn't an appropriate one, iyswim.