No jail for mum who refused baby formula

A Queensland mother who thought breast was best has avoided jail for refusing to give her malnourished child "harmful" formula.

The woman, who cannot be named because it would identify her son, pleaded guilty on Monday in the Brisbane District Court to cruelty after she ignored medical advice to top up her breastfeeding because the boy was not gaining enough weight.

By the time the five-month-old came to the attention of authorities, he only weighed 3.7kg - almost half of an average weight - and was severely malnourished.

The boy was so gaunt and emaciated his rib cage and shoulder bones were visible through the skin, his growth was stunted and he was suffering from muscle and tissue wastage.

"This child could have died," Judge David Kent said as the woman fought back tears in the dock.

"Baby formula is not harmful, it is required for babies that are not thriving on breastfeeding."

The court heard the mother-of-four had previously breastfed all of her children and feared chemicals in formula would cause harm.

Her fear of mainstream medical care and failure to see the severity of her son's condition was further impaired at the time because she was suffering from postnatal depression.

"She wanted to ask for help but couldn't," her defence lawyer said.

"She had the notion to (give formula) meant she was a failure as a mother."

The 43-year-old woman was sentenced to 18 months jail with immediate parole.

Her husband, 50, was also sentenced to 12 months jail with immediate parole for doing nothing to ensure his son was the correct weight.

The man told the court he worked six days a week to support his family financially and rarely saw his son because he was asleep when he got home.

"Perhaps my work does drive me away from home but that's what happens when you have to support everybody," he said.

The boy has made a full recovery and is back living with his parents.