About 800,000 child seats made by the Dorel Juvenile Group are being recalled by the National Highway Traffic Safety Administration.
The safety agency said it has received 143 complaints of the front harness loosening.
The recalled seats were manufactured between May 2008 and April 2009.
The seats are sold under the brand names Cosco, Eddie Bauer, Safety 1st, Maxi-Cosi and Schwinn.