In the latest fatality, the Consumer Product Safety Commission says an 8-month old girl from New Jersey suffocated while secured by a belt, trapped between the product and a crib bumper. Officials say the baby was found stuck over the side of a Nap Nanny.
The CPSC recalled more than 165,000 Nap Nanny and Nap Nanny Chill Recliners last year.
The products are no longer sold in stores. Federal regulators have issued a warning not to purchase the Nap Nanny from secondhand stores, yard sales, and auctions.
"Our message to parents is clear: Stop using it. It's dangerous," said CPSC Communications Director Scott Wolfson in an interview with ABC News. "There's been six deaths already, and we don't want another child to die unnecessarily."
He adds that it is illegal to sell the Nap Nanny in the United States.
(ABC News contributed to this report)