The U.S. Consumer Product Safety Commission (CPSC) and Fisher-Price are warning parents and caregivers about the safety of certain infant rockers after a series of infant deaths have occurred related to these rockers.

At least 13 deaths have occurred between 2009 and 2021, according to the CPSC and Fisher-Price. The Fisher-Price rockers in question are the Infant-to-Toddler Rockers and Newborn-to-Toddler Rockers. Both organizations are reminding parents and caregivers that rockers should never be used for sleep, and infants should never be unsupervised or unrestrained in these rockers.

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"Just three years ago, this agency oversaw the recall of the Fisher-Price Rock 'n Play after a staggering number of infant deaths. Tragically, we now grieve 13 more infant deaths in Fisher-Price Rockers," CPSC commissioner Rich Trumka Jr. wrote in a statement.

Infant rockers are designed to help soothe and calm babies by providing a gentle swinging motion. Other types of rockers and baby devices that have an incline—baby bouncers, infant positioners, and inclined sleepers—are not recommended by the American Academy of Pediatrics (AAP). This includes products marketed as baby nests, docks, pods, loungers, or nappers.

According to the AAP, about 3,400 infants in the United States die unexpectedly during sleep each year. This can happen from accidental suffocation, sudden infant death syndrome (SIDS), or unknown causes.

Related: Boppy recalls millions of newborn loungers after products linked to infant deaths

To help prevent these deaths, the AAP recommends that all infants should sleep on flat and firm surfaces, by themselves, without any bumpers, soft bedding, pillows or stuffed toys. Crib bumpers and inclined infant sleeper products can cause a baby to suffocate. They also advise against using products that are for infant bedsharing with parents.

The CPSC recently finalized a rule requiring that infant sleep products have a sleep surface angle of 10 degrees or less. This will go into effect on June 23, 2022.

If you've purchased any of the above infant rockers, consumers are encouraged to report incidents involving them or other infant products to CPSC at saferproducts.gov.