Inclined sleepers for infants have been controversial since Fisher-Price invented them more than a decade ago. A new study confirms the design is dangerous and deadly.

Amanda Butler's daughter, Arya, died in a Fisher-Price Rock 'n Play Sleeper.

"It's turned our life upside down," Butler said.

Nationwide, 59 babies have died in that type of sleeper since 2005, according to the Consumer Product Safety Commission. Millions of sleepers were recalled.

The safety commission's new study said that none of the inclined sleep products it examined are safe for babies to sleep. The study was led by Erin Mannen, assistant professor at the University of Arkansas for Medical Sciences.

"Babies are dying and have died in these products," said Mannen. "Based on the results of our research, it's something that has to do with the design of the product."

A Fisher-Price Rock 'n Play Sleeper. CBS News

Pediatric experts say babies should sleep flat on their backs. But some infant sleepers are set on an incline, as high as 30 degrees. Doctors say the angled position can cause the head to fall forward and block an infant's airway.

The safety commission said suffocation risk to infants disappeared when the incline was below 10 degrees. But doctors had warned of risks for years and Butler believes earlier action would have saved her daughter's life.

"Our daughter had a full life ahead of her. She only got to live ten weeks of it. I don't want anyone else to have to go through that," she said.

The safety commission is expected to vote on the tougher standard next week. It will then be open for comments.