Babies who died during their sleep while being watched by someone other than parents often had been placed in unsafe sleep positions, such as on their stomachs, or in unsafe locations, such as a couch, a new study has found.

In response to the troubling findings, the researchers are urging parents to educate anyone who cares for their children about safe sleep practices and the risk of sudden infant death syndrome (SIDS), the leading cause of death among babies between 1 month and a year of age. “If someone else—a babysitter, relative, or friend—is taking care of your baby, please make sure that they know to place your baby on the back in a crib and without any bedding,” says Rachel Moon, MD, of the University of Virginia (UVA) School of Medicine, the UVA Children’s Hospital, and UVA’s Child Health Research Center, in a release.

The researchers reviewed more than 10,000 infant deaths and found that 1,375 occurred when a parent was not present. Among those 1,375 cases, they determined:

  • Babies were less likely to be placed on their back, the sleep position recommended by the American Academy of Pediatrics, than when under parental care.
  • Babies were more likely to be placed in sleep environments with objects that might prove hazardous. The AAP recommends that sleep spaces be free of toys and soft bedding, including blankets and sleep bumpers.
  • 72.5% of licensed childcare providers placed the babies in a crib or bassinet, as recommended. Among babysitters, this number was 49.1%. Among relatives, the number was only 29.4%, and among friends it was 27.1%.
  • 54.1% of childcare providers had placed infants in the recommended supine position (on the back), compared with only 38.4% of relatives, 38.6% of friends, and 37.8% of babysitters.
  • Deaths under the supervision of friends and relatives were most likely to occur while the babies were held or placed on an adult bed.

“A lot of relatives and friends may not be aware that babies are safest on their backs,” says researcher Jeffrey Colvin, MD, of Children’s Mercy Kansas City. “They may have raised children before we knew that this was safest.”

There was some encouraging news: While past studies found that many licensed childcare providers placed infants on their stomachs to sleep, the researchers noted that that same group was now the most likely non-parental supervisor to place babies in the recommended sleep position and in cribs. They suggest this may be a result of the educational efforts of the Safe to Sleep national campaign and changes in state regulations.

“It’s always best to discuss where and how your baby should sleep,” Moon says. “You can’t make assumptions that the person with whom your baby is staying will know what is safest.”

The researchers have published their findings in the Journal of Pediatrics. The study’s authors were Elena Lagon, Moon, and Colvin.