Simmons Kids has recalled about 20,000 crib mattresses because they may not meet minimum size requirements. That could create a gap between the mattress and the crib in which children could get stuck.

More: Other Recalls, Safety Info

The U.S. Consumer Product Safety Commission said in a news release that some of the mattresses measure smaller than the 27.25-inch minimum width requirement for cribs.

The agency and the company have one report of a 6-month-old baby getting stuck, though the child was not hurt.

The recall involves open coil crib mattresses manufactured between July 1, 2006, and March 23, 2008, with a label attached to the top or side of the mattress that has the following model names:

Pottery Barn Kids by Simmons Kids Lullaby

Simmons Kids Slumber Time Evening Star Luxury Firm

Simmons Kids Baby Mattress Series 400

Simmons Kids Baby Mattress 234 Coil Count

The crib mattresses also have a law tag that is sewn into the edge of the mattress. The law tag has the date of manufacture and in most cases will contain one of the following model numbers: H59044.15.0014, M59082.15.0002, M59027.15.0002 or M59065.15.0006.

They were sold at Pottery Barn Kids and nursery furniture retailers from July 2006 through May 2008 for between $100 and $150.

The CPSC said owners should measure the mattresses without any coverings, checking the middle from the outside edge of the tape binding, with the mattress on the floor. If it is less than 27.25 inches, they should stop using it and contact Simmons Kids for a free replacement.

Consumers can call Simmons Kids at 800-810-8611 or visit SimmonsKids.com.