Millions of the popular Bumbo Baby Seats are being recalled in North America on reports of babies suffering skull fractures and other injuries after wriggling out of the pint-sized chair.

The recall applies to seats sold from August 2003 to August 2012 at children’s stores and online retailers. The recall affects more than 4.3 million chairs in the United States, and more than 340,000 in Canada.

“Infants can arch their backs and flip or maneuver out of the Bumbo seat, posing a risk of serious injuries or fall,†Health Canada said Wednesday in a .

Bumbo International, the U.S. Consumer Protection Agency and Health Canada first recalled the Bumbo Baby Seat in 2007 so a new label could be attached warning parents against using the seat on a raised surface.

Since then, Health Canada says it has received five reports of “incidents†in Canada, with three resulting in minor injury.

The CPA and Bumbo International say they are aware of at least 50 incidents since that recall in the U.S., in which babies fell from a Bumbo while on a raised surface. In 19 of those incidents, the babies sustained skull fractures.

The CPA and the company say that they are also aware of an additional 31 incidents in which babies managed to get out of the seats that were being used on a floor or at an unknown elevation, which resulted in bumps, bruises and other injuries. Two of those incidents resulted in skull fracture.

Consumers are being told to immediately stop using the seat and register for a repair kit.

Canadian consumers can call 1-866-477-5144 between 8 a.m. and 5 p.m. MT Monday to Friday in order to register for the kit, or visit the .

The kit includes a restraint belt with a warning label, a new warning sticker for the seat itself and safe-use instructions. Consumers do not need to return the seats.

The South Africa-based Bumbo International issued a statement saying the restraining belt will enhance the seat’s safety.

"The restraint belt will help prevent children from getting out of or falling from the seat when it is used as intended: on the floor with adult supervision and never on raised surfaces," said the statement.

"The health and safety of children using the Bumbo Baby Seat are our top priorities."