Police found the baby boy unharmed seven hours after the attack and have arrested and charged a 34-year-old man with inflicting grievous bodily harm.

An amber alert was activated after officers were called to an apartment complex at Southport following reports of a disturbance, shortly after 5pm on Saturday.

Finding the woman unresponsive, they established a crime scene.

Detectives are expected to allege the Crestmead man removed the infant from the location before police arrived.

The child was located safe and well around midnight and the man was arrested in Oxley shortly after 12.30am.

A grey Mazda CX9 has been seized by police as part of ongoing investigations.

The 25-year-old woman was taken to Gold Coast University Hospital with life-threatening injuries and remains in a critical condition.

The man has also been charged with strangulation and is scheduled to appear before Richlands Magistrates Court on Monday.

Australian Associated Press