Study Shows Circulatory Problems May Contribute to SIDS
March 22, 2000 (Indianapolis) -- Sleeping on the tummy, or prone position,
has been the most commonly identified risk factor in sudden infant death
syndrome (SIDS). A study in this month's journal Archives of Disease in
Childhood suggests one reason why.
The study shows that sleeping on the stomach has a measurable effect on the
body's ability to control the size of its blood vessels, such as arteries and
veins, which causes the blood vessels to dilate, or expand. This affects the
infant body's ability to control its circulation.
"We wanted to do this study as we believe that sudden infant death
syndrome is possibly linked with a problem with the circulation," says lead
author Angeline Chong, MD, from the department of pediatrics at Rotunda
Hospital in Dublin, Ireland, in an interview with WebMD. "Traditionally,
research has focused on finding a respiratory cause to sudden infant death
Forty-four full-term infants were studied during an overnight sleep.
Recordings were made while the infants were horizontal and asleep on their
backs and while they were asleep in a face-down position. Recordings were
repeated after their heads were tilted 60 degrees in each sleeping position.
Blood pressure, heart rate, and shin and abdominal wall skin temperatures were
"We found in our study that babies who were lying on their tummies were
more likely to drop their blood pressure, have a faster heart rate, and a
higher skin temperature on their legs, which to us meant that the control of
circulation was not as good when babies lie on their tummies," says Chong.
Problems in circulation could cause blood not to reach vital organs such as the
heart, lungs, and brain while an infant is sleeping. "We are still unclear
as to why babies die of SIDS, and need more research into this area. Our
findings will hopefully lead to other scientific works."
Emphasizing the uncertainty of what causes SIDS, Warren G. Guntheroth, MD,
professor of pediatrics (cardiology) at the University of Washington in
Seattle, notes that most SIDS experts think that heat stress plays a major role
in the death of these infants. The outcomes observed by the researchers in this
study could just as easily be related to the body's reactions to the buildup of
heat, Guntheroth says, adding that dilation of the blood vessels to help the
body cool off is an example.
"They have established no new category of risk in SIDS deaths," says
Guntheroth in an interview with WebMD. "Their findings of increased skin
temperature reinforce the idea put forth by myself and others that heat is the
single most neglected risk factor in SIDS. This does, however, give yet another
reason to place babies on their backs instead of their bellies."
The American Academy of Pediatrics recommends that infants not be placed for
sleep in a face-down position. Sleeping on the back has the lowest risk and is
preferred, and sleeping on the side -- while not as safe as sleeping on the
back -- has a lower risk than sleeping on the tummy.
- Sleeping on the stomach is the most commonly identified risk factor for
sudden infant death syndrome (SIDS).
- Researchers have found evidence that poor circulation control may
contribute to SIDS, as babies sleeping on their stomachs are more likely to
experience a drop in their blood pressure, faster heart rate, and higher skin
temperature on their legs.
- Though scientists still do not know what causes SIDS, many believe that
heat stress does play a role in the death of these infants.