Tributes have been laid at the home of a heavily pregnant mother-of-four who was stabbed to death, allegedly by her partner.

Kirralee Paepaerei's body was discovered by her 15-year-old son at their Mount Druitt home just after midnight on Tuesday morning.

He had left the house on Chester Street earlier that night after she and her fiancé began arguing.

The 38-year-old has now been charged with murder.

Kirralee Paepaerei was pregnant with her fifth child. (Supplied)

Tributes laid outside Kirralee Paepaerei's home. (9NEWS)

"I can’t describe how he was, he's very distraught," Detective Inspector Dave Goddard said of the teen.

Ms Paeparei’s fiancé drove himself to the local police station and told officers they had been the victims of a break-in, but was himself arrested.

"The male did drive from the premises to the police station, and walked in and presented himself at the counter," police said.

He was taken to Nepean Hospital suffering non life-threatening injuries but was released earlier today and taken to Mount Druitt Police Station where he was charged with murder.

The man was refused bail and is set to appear at Mount Druitt Local Court later today.

Ms Paeparei had four sons and was excited to be seven months pregnant with her first daughter, posting on Facebook "I'm apparently getting my pink baby".

The woman's 38-year-old partner walked into Mount Druitt Police Station shortly afterwards. (9NEWS)

Police said the woman's body was discovered by her 15-year-old son. (9NEWS)