A MUM allegedly punched her baby after it wouldn't stop crying in its pram.

The baby girl was in hospital yesterday in a stable condition recovering facial injuries.

The 29-year-old mother, from North Ward, was arrested­ at the scene and remains­ in police custody.

She will appear in Townsville Magistrates Court today to face a charge of assault occasioning­ bodily harm.

Police and paramedics rushed to Eyre St, North Ward, about 1pm on Saturday after a resident called emergency services after allegedly spotting the mother assaulting the baby in a pram on the footpath.

Witnesses reported the woman started punching the baby after it wouldn't stop crying. It is believed the baby is about five months old.

A Queensland Police spokeswoman said the baby had bruising and could have further unknown injuries.

Townsville Child Protection Investigation Unit Detective­ Senior Sergeant Dave Miles said they had launched an investigation into the incident.

Police suspect will allege the mother had been drinking before the assault. Sen-Sgt Miles said the age of the child made the alleged incident even worse.

"The child has sustained some facial injures and given the age of the child it makes it a significant concern," he said.

Sen-Sgt Miles said assaults on children were becoming a daily occurrence in Townsville. "We investigate the allegation of assaults against children every day, whether it be against babies or young children or even teenage kids. We get the full spectrum.

"There is nothing in the law for physical assault that provides for greater punishment for a baby. That will be at the discretion of the court."

Meanwhile, the alleged assault follows the revelation that convicted baby killer Troy William Reed, 34, was accused of assaulting another child one month before he murdered his partner's 16-month-old son Mason Parker in April, 2011.

Snr-Sgt Miles said anyone who witnessed the assault of a child should report it.

"If you see something that indicates a child is at immediate risk ring 000," he said.

"For any other concerns in relation to child safety or child protection, ring local police." Anyone with information should call Crime Stoppers on 1800 333 000.