Parents are more likely to follow safe infant sleep practices when doctors tell them clearly what to do and what to avoid, to minimize the chances of babies getting injured or dying during the night, a U.S. study suggests.

Researchers survey responses from more than 34,000 mothers on how often they followed four essential practices: placing infants to sleep on their back; putting babies to bed in a crib or other safe sleep surface; room sharing without bed sharing; and keeping soft objects and loose bedding away from sleeping babies.

Overall, 78 percent of mothers put babies to sleep on their backs, but just 57 percent kept babies in their room without sharing a bed with them. Only 42 percent of mothers avoided giving babies stuffed animals, pillows and other soft bedding, while just 32 percent used cribs or other safe sleep surfaces.

When mothers had been instructed on safe sleep practices by doctors, however, they were 12 percent to 28 percent more likely to put babies to bed in the safest ways, researchers report in Pediatrics.

"Placing infants to sleep on their stomach is the most widely known risk factor for sleep-related deaths, but there are other sleep-related risks that parents need to be aware of such as side sleeping, sleeping with blankets, pillows, or other soft objects, and sleeping on shared surfaces like adult beds and couches," said Ashley Hirai, lead author of the study and a senior scientist at the Health Resources and Services Administration in Rockville, Maryland.

"The safest place for babies to sleep is on their backs, on separate firm sleep surfaces (crib, bassinet, or Pack 'n Play) without any soft bedding (blankets, pillows, or bumper pads) and in the same room as caregivers," Hirai said by email.

Sudden Infant Death Syndrome (SIDS) has become much less common in recent decades as doctors have urged parents to put infants to sleep on their backs without blankets or other soft bedding and toys that could pose a suffocation risk. But it remains a leading cause of infant mortality, according to the American Academy of Pediatrics (AAP).

In the current study, demographic factors like age, race, income or education levels appeared to explain some variation - about 5 to 10 percentage points - in the proportion of mothers who said doctors told them about safe sleep practices.

But demographics explained more of the variation - about 10 to 20 percentage points - in how often mothers followed the advice.

The survey questions didn't distinguish routine habits that led to unsafe infant sleep from occasional or accidental unsafe practices.

"We don't know why families are more compliant with some of these recommendations vs others," said Dr. Michael Goodstein, division chief of WellSpan Neonatology and director of the York County Cribs for Kids Program.

"I suspect that back sleeping is one of the more commonly followed practices because we have been promoting it the longest and the 'back to sleep' campaign has been so successful in saving lives," Goodstein, who wasn't involved in the study, said by email.

Some knowledge gaps may also be cultural or generational, said Dr. Lori Feldman-Winter of Cooper Medical School of Rowan University in Camden, New Jersey.

"Many caregivers, such as young mothers, or grandmothers, who may not have been reached by the 'back to sleep' (or safe to sleep) campaigns do not know about the importance of placing a baby on his/her back as a way to prevent SIDS," Feldman-Winter, who wasn't involved in the study, said by email.