SINGAPORE - A woman who assaulted her four-year-old son so brutally that he died had her original jail term of eight years increased to 14½ years on Thursday (July 6) after the prosecution appealed.

Noraidah Mohd Yussof, 35, pushed her son repeatedly, causing him to hit his head on the floor. She also trampled on him, and grabbed him by the neck and lifted him while pushing him against a wall.

The boy died from a fractured skull and bleeding in the brain.

Noraidah was punishing her son for not reciting the numbers 11 to 18 in Malay correctly.

Last year, Noraidah was sentenced by the High Court to eight years' jail after she pleaded guilty to two counts each of causing grievous hurt and ill-treating a child. Two other counts of ill-treatment were taken into consideration during sentencing.

The prosecution appealed to the Court of Appeal for a heavier sentence of at least 12 years' jail.

On Thursday, Deputy Public Prosecutor Kow Keng Siong said the lower court was wrong in accepting Noraidah's "personality aberrations" as mitigating factors. These included a low tolerance for frustration, a tendency to act impulsively and blame others.

Mr Kow added that personality aberrations did not amount to a recognisable mental disorder. If people are entitled to lenient sentences because of their impulsive or aggressive nature, it is tantamount to giving them an excuse to give in to their emotions and act out their frustrations without self-restraint, he said.

Mr Kow said deterrence was a relevant sentencing factor. He cited statistics showing a rise in child abuse cases. Last year, the Ministry of Social and Family Development investigated 873 child abuse cases - a 60 per cent increase from 2015, when there were about 550 cases.

The apex court, comprising Chief Justice Sundaresh Menon and Judges of Appeal Tay Yong Kwang and Steven Chong, agreed with the prosecutor's arguments that Noraidah should get a longer jail term.

The Chief Justice said the gravity of the case was aggravated by the boy's young age. As his mother, she had a duty to protect him, but instead, her pattern of conduct as a whole pointed to cruelty towards the child, he added.

Noraidah started abusing the boy in 2012, when he was two. She pushed him and stepped on his ribs when he fell and also twisted his hand when he scribbled on a sofa. She later took him to hospital, where he was found to have fractures in his elbow, calf and four ribs, as well as multiple bruises.

In July 2012, the Child Protective Service (CPS) placed the boy in the care of her brother and sister-in-law. Four months later, Noraidah and her older daughter moved in with them. CPS closed the case in February 2014 after finding no further reports of abuse. Soon after, Noraidah moved out of the home with both children.