Babies who are swaddled and placed on their stomachs or sides may have an increased risk of dying from sudden infant death syndrome, according to an analysis of four studies.

Researchers found that babies who were swaddled, or wrapped tightly in a blanket or cloth, were twice as likely to die from SIDS, particularly if they were laid on their stomachs or sides, according to the report, published in the journal Pediatrics. The likelihood of SIDS was low for those placed on their backs.

In 1992, the American Academy of Pediatrics recommended that parents should place babies on their backs, instead of their stomachs, while they sleep. According to the academy, the recommendation resulted in a dramatic decrease in SIDS. But each year, there are still about 3,500 Sudden Unexpected Infant Deaths in the United States, according to the CDC.

To find out the connection between swaddling a child and SIDS, researchers pored over data from four studies which spanned over two decades and covered areas in England, Tasmania and Chicago, Ill. The studies included 760 infant deaths which were attributed to SIDS, out of a total group of 2,519 babies.

Swaddling can also be dangerous for older children who can move from their backs into a dangerous position while sleeping, Anna Pease, lead study author and research associate at the University of Bristol in England, said in a statement.

“On a practical level what parents should take away from this is that if they choose to swaddle their babies for sleep, always place them on their back, and think about when to stop swaddling for sleep as their babies get older and more able to move,” Pease said.