Infant deaths caused by accidental suffocation and strangulation in bed quadrupled between 1984 and 2004, according to a review of United States infant mortality data.

Previous studies of infant deaths have not focused on deaths caused by accidental suffocation and strangulation in bed (ASSB), wrote Carrie K. Shapiro-Mendoza, Ph.D., of the Centers for Disease Control and Prevention in Atlanta.

In this study, the researches reviewed data on infant ASSB deaths from 1984 to 2004 taken from the CDC’s National Center for Health Statistics, to include years before and after the release of revised CDC guidelines for death scene investigations in 1996 (Pediatrics 2009; 123:533-9). The change in classification of deaths may have contributed to the significant increase in ASSB deaths, they noted.

The overall rates of sudden, unexplained infant deaths remained relatively stable from 1997 through 2004, but the deaths from ASSB increased from 4% to 14% while the deaths attributed to sudden infant death syndrome (SIDS) decreased from 78% to 59%.

Based on data from 2002 to 2004 deaths among black infants were more often attributed to ASSB, compared with white infants (27 vs. 9 deaths per 100,000 live births).

The reasons for the increase in ASSB deaths remains unknown, Dr. Shapiro-Mendoza and her associates said. But based on data from 2003 to 2004, overlay was the most often reported circumstance of ASSB deaths in infants (34%), followed by suffocation by bedding (14%) and being wedged or trapped (14%), among others. In more than half of the ASSB deaths (53%), parents were sleeping in the same beds with the infants.

Safe sleep promotions, such as the Back to Sleep campaign (initiated in 1994), and a change in classification may have reduced the number of SIDS deaths, but more studies of sleep environments are needed to determine risk factors for ASSB, the researchers said.

“Prevention efforts should target those at highest risk and focus on helping caregivers provide safer sleep environments,” they wrote.

The decrease in SIDS deaths and increase in ASSB deaths suggests that other factors related to infants, sleeping environments, such as bed sharing, should be addressed. “We know from the NICHD [National Institute of Child Health and Human Development] surveys since 1992 that the incidence of bed sharing has doubled,” Dr. John Kattwinkel, professor of neonatology at the University of Virginia in Charlottesville, said in an interview.

But that doesn’t mean physicians should discourage mothers from breastfeeding in bed. “There’s nothing wrong with taking the baby to bed to breastfeed, but when it’s time to go to sleep, put the baby in its own environment,” he said.

Dr Kattwinkel chaired the American Academy of Pediatrics’ Task Force on Sudden Infant Death Syndrome during 2005-2006. The task force statement remains APP’s official stance, which is that room sharing, but not bed sharing, is the safest sleep environment for babies.

“The task force recommends that the infant’s crib or bassinet be placed in the parents’ bedroom, which, when placed close to their bed, will allow for more convenient breast-feeding and contact,” according to the statement.

A “cosleeper” bed that attached to the mother’s bed provides another option, although the safety of these products has not been established or well studied, Dr. Kattwinkel added.

The researchers state they had no financial conflicts to disclose.