Care agencies failed to spot warning signs about a mother convicted of inflicting "horrific" injuries on her two month-old baby, a report has found.
Claire Biggs, of Newham, east London, fractured her son Rhys's ribs by crushing him, her trial was told.
Biggs was convicted of assault at Inner London Crown Court and her partner Paul Husband was found guilty of neglect.
The serious case review found the decision not to begin child protection measures was "over-optimistic".
The baby died on 8 May 2006 and had a series of injuries including 17 broken ribs, a broken shoulder and a fractured arm.
Rhys came under the care of health workers in two London boroughs, first in Newham and then Camden.
The court heard care workers were unable to check on Rhys because Biggs repeatedly failed to keep appointments with them.
The report, which was completed in 2006 but made public on Wednesday, studied how various agencies dealt with Biggs while she was pregnant and during Rhys's life.
It found that although the boy's death could not "reasonably have been anticipated", the agencies failed to spot warning signs.
The court heard Biggs previously had a daughter who was taken into care in 2001, when Biggs was homeless and addicted to crack cocaine.
Biggs, who had been the victim of domestic violence and had lived in shelters, also had learning difficulties which were not fully assessed.
Background checks on Husband were never carried out because the nature of their relationship was unclear and when Biggs split from Rhys's father and began the relationship with Husband, agencies failed to mention it to social workers.
The review found the agencies involved should have been more careful because of the woman's previous history of domestic violence.
Camden Council's approach was found to be "satisfactory" but the report said: "The decision not to implement child protection arrangements was over-optimistic and was not adequately challenged.
"Some agencies were not sufficiently mindful of their statutory obligation to safeguard and promote the welfare of children, and that this applies equally to unborn children."
Kim Bromley-Derry, executive director for children and young people at Newham Council said: "We would like to reiterate that all the agencies involved with this case are very sorry about what happened to young Rhys.
"The independent review identified some areas where improvements can be made by all the agencies involved.
"It also found no evidence that the tragic death of Rhys could reasonably have been anticipated by the agencies involved.
"We want to continue to learn from this incident and now that the case has finished, we will review action plans again to identify any further areas for improvement or action."