SCIENTIFIC NEWS
PERICONCEPTIONAL AND FIRST TRIMESTER ALCOHOL CONSUMPTION
MAY BE ASSOCIATED WITH SUDDEN INFANT DEATH SYNDROME.
Raanan Cohen-Kerem MD, Postgraduate Trainee, Motherisk Program, Toronto
A CRITICAL REVIEW of "Risk factors
for sudden infant death syndrome among
northern plains Indians." Iyasu S, Randall
LL, Welty TK, Hsia J, Kinney HC, Mandell F,
McClain M, Randall B, Habbe D, Wilson H,
Willinger M. JAMA 2002;288:2717-23.
T
he objective of Iyasu and colleagues’
was to determine the prenatal and
postnatal risk factors for sudden infant
death syndrome (SIDS) among American
Indians given the fact that SIDS is a leading
cause of postnatal mortality in this population.
The design was a population-based case
control study of 33 SIDS infants and 66
matched living controls among American
Indians enrolled from December 1992 through
November 1996.
Eligible cases were American Indian
infants, residing on or near reserves or
participating communities whom either of their
parents was a tribal member, and who died
before one year of age. Infants who died
during their delivery hospitalization were
excluded. Cases were retrieved from public
health nurse reports, medical record
department staff, members of the Perinatal
Infant Mortality Review Committee, from
death certificates, and obituaries in local
newspapers. Two living control infants were
matched to each case by postnatal age and
community or reservation of residence. Data
was collected retrospectively. Information
retrieved
included
information
about
demographic factors; maternal medical and
obstetric history; and a wide range of potential
risk factors (cigarette smoking, alcohol
consumption, drugs of abuse, etc.). The
authors used standardized autopsy and
standard death scene investigation protocols.
The Perinatal Infant Mortality Review
Committee confirmed a diagnosis of SIDS
only if there was sufficient information from
the autopsy and scene. The main outcome
measure was association of SIDS with
maternal socioeconomic and behavioral
factors, health care utilization, and infant care
practice. Maternal drinking was approached in
two ways: 1. Maternal drinking in the period of
3 months before pregnancy and in the first
trimester; 2. first trimester binge drinking.
Out of 72 deceased American Indian
infants younger than one year, 37 succumbed
to SIDS. Data were retrieved for 33 cases from
questionnaires and reports and were matched
to 66 control infants. The mean age at death
was 109 days; 51.5% of the infants were male
and 64.7% died during the autumn and winter
months. According to this study, the typical
American Indian family experiencing SIDS
include a 24.4-year-old mother and a 26.5year-old father. Their level of education was
10.9 and 11.7 years respectively and their
monthly household income was US$723.40
significantly lower than in the control group.
The home crowding index was 140.7% (total
number of persons living in household divided
by the total number of rooms, times 100). A
SIDS case was typically a term baby born to a
3.7 gravid woman with a normal birth weight.
The typical SIDS case had 2.8 well-baby visits
and 8.9 prenatal care visits. All these
parameters were similar to those in the control
group.
In a univariate analysis the researchers
found that first trimester drinking was more
prevalent in cases (unadjusted OR 6.7, 95% CI
2.2-20.1; 1.9 drinking days per month vs. 1.1
for control mothers, p<0.03). First trimester
binge drinking was associated with a 6-fold
J FAS Int 2003;1:e6 April 2003
© The Hospital for Sick Children 2003
increased risk for SIDS (unadjusted OR 6.3,
95% CI 1.8-22.8), 4.8 days of binge drinking
vs. 2.6 (p<0.08). Alcohol consumption was not
statistically different between the groups in the
second and third trimesters. Maternal
nutritional status and hematocrit were not
found to be a significant factor in the risk for
SIDS.
here may help in applying them to the general
population. As the authors are pointing out,
this is the first time an association between
maternal
alcohol
consumption
(periconceptionally or first-trimester binge
drinking) and the risk for SIDS has been
clearly established although suggestions for
this association had been published in the past.
Other significant sociodemographic and
health related factors were: Parents of SIDS
cases were mote likely to have more than 12
years of education (unadjusted OR 8.8, 95% CI
1.1-70.8) and were less likely to have a
telephone at home (unadjusted OR 0.3, 95% CI
0.1-0.8). A case mother was less likely to have
prenatal care visits and home visits by public
health nurses and was more likely to have
transportation problems for prenatal care. A
SIDS case was more likely to have fewer wellbaby visits than its control (unadjusted OR
13.8, 95% CI 1.7-109.9) and was more likely
to have more than 2 layers of clothing than
control babies (unadjusted OR 3.9, 95% CI
1.4-10.9).
The authors were able to keep track of
more than 80% of the case subjects and used
equal and reliable measurements in both
groups addressing the specific problem of
SIDS considering all important outcomes.
Of the factors known to be causative for
SIDS - maternal smoking was not found to be
a risk factor for SIDS in this population nor
were drugs of abuse. As importantly,
positioning of the baby (prone or supine) was
not different between the groups.
In a conditional logistic regression,
periconceptional and first trimester binge
drinking were associated with an increased risk
for SIDS (adjusted OR 6.2; CI 1.6-23.3 and
8.2; CI 1.9-35.3, respectively). Two or more
layers of clothing (adjusted OR 6.2; CI 1.426.5) and fewer visits by the public health
nurse (adjusted OR 0.2; CI 0.1-0.8) were also
significant risk factors for SIDS.
The authors recognize limitations, which
result from the study design. The sample size
was under-powered to recognize risk factors
associated with smoking and gestational age,
but was sufficient to detect other positive
associations. Of interest is positioning of the
child (prone), that shown as a major
determinant of SIDS in other studies, but not in
the current one. Recall bias is one of the major
pitfalls in studies using retrospective data
collection. Parents of SIDS cases will tend to
remember more details associated with the
deceased baby’s pregnancy, whereas parents in
the healthy control group may remember fewer
details. This source of bias can be overcome by
having a control group of children who died
due to other causes, hence ensuring a similar
pattern of recall. Still, results suggest that
prevention of alcohol consumption in women
in childbearing age may decrease the risk of
SIDS. Other factors, such as visits by public
health nurse and layers of clothing for the
infant should be a target for more research as
well.
This study is aimed at identifying risk
factors for a major health issue. Addressing
these risk factors may shed light on the
etiology and may enable us to recognize the
appropriate interventions needed to prevent
SIDS. The rate of SIDS among American
Indians is higher than in the general
population, but identification of risk factors
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J FAS Int 2003;1:e6 April 2003
© The Hospital for Sick Children 2003