Three years ago, Dr. Bradley Thach, a professor of pediatrics at Washington University in St. Louis, published findings that had the potential to upend nurseries across the nation, and perhaps save some lives too.

In reviewing data from the Consumer Products Safety Commission, Dr. Thach concluded that crib bumpers  the padding wrapped around the inside of a crib that often matches the beddingwere killing babies. In a 10-year period beginning in 1995, he found 27 suffocation deaths involving bumper pads, and he theorized that many more might have occurred because of inconsistencies in the data.

“Because bumpers can cause death, we conclude that they should not be used,” he warned.

The Consumer Products Safety Commission initially ignored the findings. Last summer, it reached the same conclusion as a trade group representing product manufacturers, which asserted that other factors, like a crib crowded with pillows or babies sleeping on their stomachs, might have been a factor in those deaths, rather than the bumpers. As a result, most parents remained unaware of the debate over the safety of crib bumpers.

Now, prompted by consumer advocates and news reports highlighting potential dangers, the commission has reversed itself and decided to take a deeper look at crib bumpers as part of a broader regulatory crackdown on the hazards of an extensive line of baby sleep products that have been blamed for more injuries and deaths.