The NIH this week revealed results from the National Infant Sleep Position Study that show that the incidence of infants sharing a bed with an adult or another child has more than doubled over the past two decades. Nearly 14% of infant caregivers surveyed in 2010 stated that their baby regularly shared a bed with another person. This is up from just 6.5% who said the same thing back in 1993.

The practice of infants sleeping with adults is known to increase the risk of sudden infant death syndrome (SIDS), the unexplained death of an infant. Doctors recommend that infants sleep in the same room as parents, but not in the same bed.

The new study, published in the Journal of the American Medical Association Pediatrics, also shows there is a wide disparity in infant bed-sharing practices across different ethnic groups. Though the practice increased for all ethnic groups, only 9.1% of white infants were found to share a bed in 2010. This is less than half of the 20.5% of Hispanic infants that were reported to share a bed in 2010, and far less than the 38.7% of black babies that reported to share a bed that same year.

“The disparity in nighttime habits has increased in recent years,” said Dr. Eve Colson, first author on the study and a researcher at the Yale University School of Medicine. “Because African-American infants are already at increased risk for SIDS, this trend is a cause for concern.”

The study’s authors suggest that advice from doctors can reduce the practice of infant bed-sharing. The study found that parents who knew their doctor was against sleeping with an infant were more than one-third less likely to say they share a bed with their baby.

“It’s important for doctors to discuss sleeptime habits with new parents in order to convey the risks of bed sharing clearly,” said Marian Willinger, co-author of the study and a SIDS researcher at the National Institute of Child Health and Human Development.