The pair was rushed to hospital after the woman's partner allegedly bashed them.
Terrance Cameron's grandchildren alerted authorities to a case of serious assault after discovering their 67-year-old grandfather lying on the ground with blood pooling from his head.
Midland Detectives said Mr Cameron was running to the aid of his pregnant neighbour when the woman's partner began punching her in the back of the head out the front of their Swan View home, east of Perth.
Around 8.30pm on Saturday night a verbal dispute between the man and pregnant woman broke out on Buckingham Road in Swan View before turning violent.
It'll be alleged the man punched the female victim in the back of the head, causing her to fall to the ground, before continuing to kick and punch her.
It was at this time Terrance Cameron rushed from his home, where his two grandchildren were inside, to interview between the man and woman.
Police said Mr Cameron, who was armed with a metal pole to defend himself, was then knocked unconscious after his 31-year-old neighbour punched him in the face, causing Mr Cameron to fall head-first backwards onto the road.
The victim's 14-year-old grandson, Zachary, rushed outside to find Terrance on the road and immediately called triple zero.
The man continued to assault the pregnant woman with a wooden object as other family members attempted to stop him. He then fled the scene.
St John's ambulance officers arrived at the scene and rushed Mr Cameron to hospital. He received a fractured skull, broken nose and a possible fractured cheek.
The woman was treated for bruising to her torso.
Police found the man around 11pm on Saturday night and have charged him with a string of offences including aggravated grievous bodily harm.
He'll appear in Midland Magistrates Court today.
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