Commissioner Nancy Nord, a Republican, voted against the rule.
She objected to the commission’s decision to require a new method of testing the flatness of mattresses, rather than using the one companies already use voluntarily.
“After reviewing the evidence available and staff’s analyses of it, I am convinced that the two criteria are materially identical,” she said in a statement after the Sept. 30 vote.
Bassinets are small standing beds that can rock or stand stationary.
From November 2007 to March 2013, 132 babies died in bassinets, according to the safety commission, as part of 426 total incidents. Those deaths often occur when babies are suffocated by extra bedding in the bassinet or when they are wedged between the bedding and the side of the cradle.
The new rules stem from a 2008 law requiring the CPSC to issue safety standards for infant and toddler products.
The agency first proposed a standard in 2010, and followed that up with a second proposal last October.
The standard becomes effective in six months. Manufacturers will have another 12 months to comply with a provision on removable bassinet beds.