IIRC from watching a blurb from the only juror to consent to an interview, they did consider manslaughter. The sticking point was the lack of ability to show cause of death. On that basis I have to partially agree with what she said. The prosecution simply lacked the evidence. This may just have been one of the few that will have to have slipped between the cracks of the justice system. It is not a presumption of guilt, of that there was and is plenty. It is a case of beyond a reasonable doubt and there was not enough of direct provable evidence to lead to the conclusion that she, or her mother, or her father were the ones to have done the deed.
IMO she did murder her child. That she was found not guilty does not mean she did not do it, it just means that she was not convicted of doing it. Sometimes things happen that cannot meet the requirements of the courts, irregardless of the actual events.
The child deserved a better family but didn't get it. May she rest in peace.