Emma Cartwright and partner Neil Gleaves, both 27, left the child with six broken bones for two days before taking the child to hospital.
They were given suspended sentences because it was their first offence.
But Cartwright's former friend, Nicola Linyard, 29, was so incensed by the sentence that she wrote to the Government demanding the couple were jailed – and now the couple could be jailed for a maximum of 10 years.
The Attorney General asked the Crown Prosecution Service (CPS) to pass on details about the case and a decision will then be made on whether to send the case to the Court of Appeal for a sentence review.
Nicola, from Wolstanton, Staffordshire, told her local newspaper: "People here are absolutely disgusted with the sentence and they both deserve to be jailed.
"The sentence is unbelievable. It's like the judge is sending out a message to say that it's OK to be cruel to children.
"Drink-drivers get sent straight down, but these two have been allowed to walk free. I'm glad the Attorney General has listened to the protests and I hope it leads to them being given a proper sentence - in prison."
Stoke-on-Trent Crown Court heard X-rays revealed the child had suffered a catalogue of fractures to both arms, both legs, the left foot and left shoulder.
The child was also shaken by Gleaves, while a second child was slapped by Cartwright.
The judge, Recorder Simon Ward gave them each a 36 week prison sentence suspended. Gleaves was also ordered to complete 100 hours of unpaid work. The couple have left the area.
He told them: "You've both been convicted of very serious offences and you're going to have to live with the consequences.
"Offences of cruelty and ill-treatment of children are so serious that the courts have to send out a message to people that, if convicted, serious sentences will follow."
A spokesman for the Attorney General's Office said: "We have asked the CPS for more information to decide whether the sentence should be referred to the Court of Appeal for review."