It is horrendous and heartbreaking work but possibly the most important job there is.

NSW Police Force's child abuse squad is responsible for investigating almost 5000 alleged cases of sexual and physical abuse against children each year.

The squad's boss, Detective Superintendent Greig Newbery, says his officers investigate the most horrific crimes most people preferred to ignore.

"It's difficult but you know it's worth it," he said.

"Our jobs aren't pleasant. But we do them passionately – my people are fantastic. They are the ones sticking up for the most vulnerable in the community."

The father of three said his squad was the largest in the force, with 183 officers based in 23 locations throughout NSW.

"[There are] horrendous assaults on these kids. There are babies who can't stand up for themselves, they can't do anything. The biggest offence they have committed [sometimes] is not being able to sleep."

In recent months there had been a spate of chilling child abuse cases, including a nine-month-old baby left in a critical condition after he was allegedly attacked at Lalor Park in Sydney's west.

A man and woman were also before the courts after a two-year-old boy was left with life-threatening head injuries at his North Rocks home in August.

Just a month later a seven-month-old boy underwent surgery for critical injuries to his head and body after he was abused on the central coast.

"We've had a number of theses matters come up of late," Superintendent Newbery said.

"They're all isolated incidents, and I would hope we don't see any for a long time.

"Kids that suffer theses traumatic incidents, they have to live with them for a long time after."

The state is split up into four zones and each is headed by an inspector who oversees the investigations in that region.

Many of Newbery's officers work in the same space as the Department of Family and Community Services and NSW Health.

Officers in the squad undergo mandatory welfare checks with psychologists every three months and are rotated out of the team every three years.

The squad was recently renamed after being previously called the Joint Investigation Response Team.

Part of the rebranding has led to an increase in arrests and a better public awareness about child abuse.

"We need to ensure that people who know something, do something," he said.

Child Protection Helpline on 132 111