Megan Huntsman, 39, gave birth to the babies between 1996 and 2006.

Seven bodies were found by police at the house in Pleasant Grove; it is unclear why she has only been charged on six counts.

Her estranged husband, who has not been charged, discovered the first body in the garage before alerting authorities.

Megan Huntsman was charged with six counts of murder at Utah Country Jail on Sunday.

Darren West, who has himself been in prison recently on drug-related charges, is believed to have been her partner when the children were born.

"We don't believe he had any knowledge of the situation," police spokesman Michael Roberts said.

When asked how the husband could not have known his wife had given birth to seven children, Mr Roberts replied: "That's the million-dollar question. Amazing."

The bodies were discovered stuffed into separate cardboard boxes in a garage

Neighbours said they were unaware of unusual activity at the house

Police officers "got more and more shocked with each box they opened", he added.

The bodies have been sent to a medical examiner for testing.

DNA samples taken from Megan Huntsman and her husband will be used to confirm the identity of the parents.

On Sunday, Darren West's family said they were in a "state of shock and confusion."

Mrs Huntsman had moved out of the house around three years ago,

She had three daughters, a teenager and two adults, who had continued to live there.

The daughters seemed "normal", neighbour Vickie Nelson told the Associated Press.

They did not seem to know their mother was pregnant or notice anything suspicious, neighbours said.