Researchers have conducted the most definitive study of its
kind to show that sleeping on the stomach increases the
risk of U.S. infants for Sudden Infant Death Syndrome
(SIDS). Previously, researchers had relied largely on
overseas studies for making the recommendation that infants
be placed on the back to sleep in order to reduce their
risk for SIDS.
The study focused primarily on SIDS cases among African
Americans, a group at roughly twice the risk for SIDS than
are Caucasians.
The findings appear in "Pediatrics," October 2002. The
research was supported by the National Institute of Child
Health and Human Development (NICHD), the National
Institute on Deafness and other Communication Disorders,
and the Centers for Disease Control and Prevention.
The study results provide strong support for the American
Academy of Pediatrics' 1992 and 1996 recommendations that
infants be placed to sleep on their backs to reduce the
risk of SIDS. The research also underscores the urgency of
current programs to ensure that African Americans receive
this recommendation.
"This is the largest, most comprehensive study of SIDS risk
in an urban, high-risk setting," said Duane Alexander,
M.D., Director of the NICHD. "Other studies have linked
sleeping on the stomach with Sudden Infant Death Syndrome,
but the Chicago Infant Mortality Study makes the strongest
case to date."
"Racial and ethnic disparities in infant mortality have
been among the most persistent in our society," said James
Marks, M.D., director of CDC's chronic disease program.
"This study suggests that at least some of the disparity
can be eliminated by wide use of the supine [back] sleeping
position among African-American infants."
In their study, the researchers used the NICHD definition
of SIDS: "the sudden death of an infant under one year of
age, which remains unexplained after a thorough case
investigation, including performance of a complete autopsy,
examination of the death scene, and review of the clinical
history." In all, the researchers examined the records of
260 infants from the ages of birth to one year who had died
of SIDS in Chicago, Ill. between November 1993 and April
1996. Of these, 75 percent were African American, 13
percent were white, Hispanic, and another 12 percent were
white, non-Hispanic.
The study was conducted in Chicago because that city has a
large African American community. The researchers compared
information about each infant to information about a
control infant -- a living infant of comparable age, who
was from the same racial and or ethnic group, and who had a
similar birth weight. All of the SIDS deaths were
evaluated by the Cook County medical examiner's office;
autopsies had been conducted to rule out other causes of
death. Death scene investigators conducted interviews
about circumstances surrounding the deaths. Roughly two
weeks after the death, another interview was conducted with
the infant's primary caregiver. This interview included
questions not included on the death scene investigation,
such as the infant's routine sleep patterns and access to
health care.
The current study found that African Americans at that time
were less likely than Caucasians to have been informed by
health care personnel to avoid placing infants to sleep on
the stomach. Most of the SIDS deaths occurred within the
first four months of life, with most of these occurring
between the first month and the third month. Consistent
with other studies, most of the SIDS infants had died in
the fall or winter--64 percent.
The percentage of stomach sleeping for the infant's last
sleep was similar in all of the SIDS infants--58 percent
among African Americans, and 55 percent for all other
ethnic groups. Among the control group, 43 percent of
African Americans were usually placed to sleep on their
stomachs, compared to 12 percent for the other groups.
Infants placed to sleep on their stomachs were at more than
twice the risk for SIDS as were infants sleeping in other
positions.
"Our study highlights the need for health care
professionals to inform parents of all racial and ethnic
backgrounds about the importance of placing their infants
to sleep on their backs," said the study's principal
investigator, Fern R. Hauck, M.D., M.S., now with the
Department of Family Medicine, University of Virginia
Health System in Charlottesville.
For the control group, 64 percent of mothers said that a
doctor or nurse had advised them after delivery about
infant sleeping position. The most common recommendation
was that infants be placed to sleep on their sides,
consistent with recommendations at that time. The next
most common recommendation was that infants be placed to
sleep on their stomachs. The study authors theorized that,
at the time, many health care professionals feared that
infants placed to sleep on their backs might choke on vomit
if they happened to spit up during the night. In contrast,
only 46 percent of those whose infants had died of SIDS
said they had received advice from health care
professionals on how to place their infants for sleep. For
both the SIDS infants and controls, a greater proportion of
African Americans (25 percent) than Caucasians (7 percent)
said they had been advised to place their infants to sleep
on their stomachs.
In 1992, the American Academy of Pediatrics recommended
that infants not be placed to sleep on their stomachs.
(The AAP revised this recommendation in 1996, to say that
placement on the back is the preferred sleeping position
for all healthy infants.) These recommendations were based
on studies of infants from New Zealand, Australia, and the
United Kingdom. However, few studies had been conducted
specifically on whether stomach sleeping increased U.S.
infants' risk for SIDS. The Chicago Infant Mortality Study
sought to determine if the stomach sleeping position
contributed to SIDS in an urban, African American
population at high risk for the condition. The study
authors described the 1991 Chicago SIDS rate as "alarmingly
high" -- 2.6 SIDS deaths per 1000 live births, as compared
to the overall U.S. rate of 1.3.
The current study is part of a body of research sponsored
by the NICHD on infant sleep practices and the causes of
SIDS. This large body of research, together with
compelling scientific evidence from around the world,
confirmed the safety and effectiveness of back sleeping.
Based on this evidence, the NICHD formed a coalition of
national organizations to launch a national public
awareness campaign called "Back to Sleep" in 1994. Along
with NICHD, the coalition consisted of the Health Resources
and Services Administration, the American Academy of
Pediatrics, the Association of SIDS and Infant Mortality
Programs (formerly the Association of SIDS Program
Professionals), and the SIDS Alliance. At that time, the
SIDS rates for African Americans were double those for
Caucasians. (See chart at
http://www.nichd.nih.gov/sids/sidsrates.pdf.) Since the
start of the NICHD-led campaign in 1994, the SIDS rates for
both groups have declined by about 50 percent, but a
significant disparity still remains. To help eliminate
this disparity, the NICHD joined with the non-profit
National Black Child Development Institute in a program to
reduce SIDS among African American infants in Chicago and
around the country. The Alpha Kappa Alpha sorority, the
Women of the NAACP, and the Coalition of 100 Black Women
are among the many organizations that have joined in this
effort. More information about this outreach program is
available on the NICHD Web site at
(http://www.nichd.nih.gov/sids).
One of the strengths of the current study is that it used
standard criteria for evaluating all potential SIDS deaths,
making it easy to compare details among the cases. In
prior studies, the SIDS cases sometimes had been evaluated
under a number of different standards. Similarly, the
researchers conducted an extensive investigation of the
death scene that involved asking the infants' caregivers
detailed questions. These included questions about: the
events preceding the infant's death, discovery of the
deceased infant, the medical history of the infant and
family, as well as maternal alcohol, tobacco, and drug
abuse before and during pregnancy.
The study relied primarily on the ability of mothers and
family members to recall events regarding the infant's last
sleep. The study authors noted that mothers who had lost
their infants to SIDS may have been better able to recall
the circumstances surrounding their infant's last sleep
than were the mothers of the control infants. The study
authors do not believe this possibility is likely, however,
as both cases and controls were interviewed within a short
time of their infants' last sleep period. |
