A nurse had her one-year-old son taken away after concerns were raised over her parenting.
A social worker told a private family court hearing in Reading she had concerns about the woman's "basic parenting skills".
She said the woman had also not fed her son or changed his nappy appropriately.
Judge Eleanor Owens ruled the boy should live with relatives. She added the child would be able to stay in touch with his mother.
The judge described the mother as having an "extremely low range" of intellectual ability.
The social worker described how she had watched the woman "spend about an hour holding the boy who was sitting in the Bob the Builder car".
She said the mother "maintained limited eye contact and communication" and that the toy car was "inappropriate" for his age because there was "a potential risk of the boy falling if the woman lost control of him".
Judge Owens said all professionals involved were concerned about the woman's "lack of insight" and "ability to meet the needs of the boy".
She said the social worker had "highlighted" some of those concerns.
"These include...not feeding the boy in an appropriate position, not changing his nappy appropriately, and placing his nappy changing mat very close to a metal table leg when he was moving around on the mat," the judge explained in her ruling.