(RxWiki News) A baby's first few years involve reaching several motor development milestones. One of these is rolling over. But have changes in sleep guidelines affected when kids first roll over?
Apparently not, according to a recent study. New guidelines for babies to sleep on their backs were introduced in 1992.
The recommendation to have babies sleep on their backs has appeared to reduce rates of sudden infant death syndrome (SIDS).
At the same time, the change to babies' sleeping on their backs has not affected when babies first start rolling over by themselves.
Babies typically learn to roll over some time between 4 and 6 months old.
"Ask your pediatrician about "tummy time"."
The study, led by Johanna Darrah, of the Department of Physical Therapy at the University of Alberta in Edmonton, Canada, looked at whether new sleeping guidelines for babies have affected one motor development milestone.
The researchers analyzed data on babies' motor development milestones gathered before the new sleeping guidelines were issued in 1992.
They compared the average ages when babies reached the milestone of rolling over before those guidelines to the average ages today.
The first group of babies studied (before 1992) included 1,114 babies (about half male and female) who were less than 9 months old.
The second group of babies studied in the present day included 351 babies who were also under 9 months old.
Comparisons between these groups showed that babies still meet each of the four rolling over milestones in the same order at about the same ages as they used to.
Babies typically learn to do an immature roll before a mature roll. The difference between these is whether a baby fully rotates their trunk (midsection) during the roll.
In the babies studied before 1992, most first learned to do an immature roll from their backs to their stomachs and then, very soon afterward, learned an immature roll from their stomachs to their backs.
In the present day group of babies, the children met both these milestones at the same proportion (about the same time).
Then babies in both groups learned to fully roll (while rotating their trunk) from their backs to their tummies. Then they learned to fully roll from their tummies to their backs.
"The present analyses suggest that infant rolling abilities are very much the same as they were 20 years ago and that new age guidelines for rolling are not needed," the authors wrote.
When babies began sleeping on their backs, some professionals in the physical therapy field worried that babies would be delayed in rolling from their tummies to their backs because they were on their stomachs less.
"Infant gross motor development hasn't changed that much in 20 years," Dr. Darrah said in a prepared statement.
"The thought that babies first roll from their tummy to their back, before they go from their back to their tummy, does not appear to be the case," she said. "For most babies, they happen very close together."
The study was published June 3 in the journal Early Human Development.
The research was funded by the Canadian Institutes of Health Research. The only conflict of interest noted was that the primary author receives royalties for a textbook called Motor Assessment of the Developing Infant.