Joseph Martyak, a safety commission spokesman, said alerts were useful.
“It’s better to give people a heads-up in these situations,” he said. Deciding on whether a recall is needed “takes time,” he said.
“The agency has to get the company to agree to the voluntary recall for it to happen,” he added.
Soon after the Rock ’n Play was introduced, Dr. Natasha Burgert, a pediatrician in Kansas City, Mo., began to warn parents against it, often unsuccessfully.
“Most families believed that since the product was from a reliable company, our concerns as pediatricians were seen as alarmist and overzealous,” she said. “The box specifically suggested ways of safe use, and parenting blogs galore were touting its utility and ‘lifesaving’ sleep help.”
Stuart Brazell, an actress and blogger in Los Angeles, described her experience with the Rock ’n Play as “amazing.” She began using it the day she brought her son, Asher, home from the hospital last year.
Ms. Brazell, who has 157,000 followers on Instagram, said she had heard that Fisher-Price was seeking mothers for a Rock ’n Play social media campaign. She signed up through an agency that links so-called social media influencers to brands.
The agency gave her specific instructions for her post — the sleeper had to rest on a level surface, and her son had to be buckled into the harness — and approved the image and caption before she published it in November, she said. The post earned more than 4,000 likes.
“The power of social media is major for moms,” she said. “A lot of the time, we’re stuck at home and sometimes the only contact we have with other people is online.”
Asher is now 9 months old. Ms. Brazell stopped using the Rock ’n Play when he began to roll over.
“We kept the Rock ’n Play in the garage for baby No. 2 if we had another one,” she said, “but I’m completely torn now as to what to do.”