Key Points:

Police say a "tragic and freak accident" claimed the life of a mother and her 10-month-old son at their Lincoln home south of Christchurch yesterday.

Police said it appeared the woman, Irene Skurr, 36, was feeding her infant son, Cameron John McDrury, when she died as a result of deep vein thrombosis - a blood clot.

Sergeant Danny Harker, of Lincoln police, said it appeared the baby had been smothered by his mother's body.

"There are no suspicious circumstances and this is a tragic and freak accident that has traumatised the family," Mr Harker said.

"We ask that the family's privacy be respected for them to grieve."

The case had been referred to the coroner for an inquest.

Mr Harker said the final cause of death and findings would be released by the Coroner's Court.