The Evidence
Ed Mitchell
Department of Paediatrics, University of Auckland
Auckland, New Zealand
9 October 2013
MoH Safe Sleep – How to protect your baby:
• Put your baby to sleep on their back with their face up.
• Ensure your baby’s face is clear of bedding and they can’t get
trapped or strangled. Avoid using pillows and bumper pads;
don’t put baby down on soft surfaces; make sure there are no
loose blankets; remove any cords from bedding; ensure there
are no gaps in their bed. (Unintentional suffocation)
• Your baby is safest in their own bed (a cot, bassinette,
wahakura or pepipod) and in the same room as their
parent/caregiver (when the parent/caregiver is also asleep).
Babies shouldn’t sleep in bed with another person (either adult
or child).
• Your baby should be smokefree in the womb and after birth.
Also make sure friends and family don’t smoke around baby.
• If possible, breastfeed your baby.
Outline
• Sleeping position
• Smokefree
• Breastfeeding
• Sleeping in the parental bedroom
• Bed sharing
• Accidental suffocation
Sleeping position
• Overwhelming evidence from case-control studies
that prone sleeping position is associated with SIDS
• The recommendation that placing infants to sleep on
their back (“Back to Sleep”) has been associated with
a dramatic fall in SIDS mortality
• Infant care practice surveys show that few infants are
placed prone to sleep
• Thus prone sleeping position as a risk factor has
largely been eliminated
Unaccustomed to prone sleeping
Usual
Last sleep
Cases
Controls
Adj OR
Non-prone
Non-prone
37%
62%
1.0
Prone
Non-prone
3%
2%
3.0
Non-prone
Prone
8%
1%
19.3
Prone
Prone
56%
32%
4.6
• Infants unaccustomed to the prone sleep position are
at much greater risk for SIDS when placed prone
than if they had been used to prone sleeping.
• It is uncertain why the infants were placed prone, but
it does emphasise that all caregivers, such as
grandparents, need to know the preferred sleeping
position is supine.
Risk of SIDS associated with side sleeping
position compared with back
At least 10 published studies
New Zealand, Australia, UK, US, Germany,
Scandinavia
Pooled OR=2.0 (95% CI=1.7, 2.4)
Side sleeping position is unstable with infants mostly
rolling onto their back, but occasionally rolling onto
their front. This has been called “secondary prone”.
Conclusion:
Infants placed supine (back) to sleep are at the lowest
risk of SIDS, which supports the recommendation that
this is the preferred sleeping position of healthy
infants.
Risk of SIDS associated with maternal smoking
in pregnancy
• 52 studies prior to “Back to Sleep” campaigns
• At least 17 studies since “Back to Sleep”
• These come from UK, US, NZ, Germany,
Scandinavia, Netherlands
• All showed an increased risk
• Pooled OR = 3.9 (3.8-4.1)
Risk of SIDS associated with father’s smoking
where the mother is a non-smoker
7 studies
From UK (3), New Zealand (2), Scandinavia (2), Europe (1)
Pooled OR = 1.5 (95% CI = 1.2, 1.8)
Conclusions: Smoking and SIDS
• There is substantial evidence that maternal
smoking in pregnancy causes SIDS (OR = 3.9)
• The effect of environmental tobacco smoking
(ETS) is small, but statistically significant
• The predominant effect from maternal smoking is
likely to be in utero exposure of the fetus
Amount smoked by mother
Amount smoked by the mother
Implications
Using the odds ratios in the DH figure, reducing
maternal smoking from 20+ cigarettes per day to 1019/day lowers the risk by a quarter, whereas getting
those who smoke 1-9/day to stop lowers their risk by
three quarters.
Breastfeeding and reduced risk of SIDS:
A meta-analysis (Hauck et al, 2011)
• Identified 23 studies
• Pooled univariate OR = 0.49 (95% CI=0.45-0.53)
• However, this might represent confounding by
socioeconomic status
• 9 studies reported multivariate risk which included
adjustment for socioeconomic status
Multivariable analysis of any breastfeeding versus no
breastfeeding (N=9)
Study or Subgroup
log[]
SE Weight
IV, Fixed, 95% CI
Chen 2004
-0.17435 0.114609
48.3%
0.84 [0.67, 1.05]
Fleming 1996
0.058269 0.317657
6.3%
1.06 [0.57, 1.98]
Hauck 2003
-0.91629 0.319582
6.2%
0.40 [0.21, 0.75]
Jonville-Bera 2001
-0.59784 0.307136
6.7%
0.55 [0.30, 1.00]
Mitchell 1997
-0.07257 0.420337
3.6%
0.93 [0.41, 2.12]
Ponsonby 1995
-0.15082 0.401245
3.9%
0.86 [0.39, 1.89]
Stray-Pedersen 2005
-1.42712
0.86918
0.8%
0.24 [0.04, 1.32]
Vennemann 2009
-0.84397 0.239354
11.1%
0.43 [0.27, 0.69]
13.1%
0.50 [0.33, 0.77]
100.0%
0.68 [0.58, 0.80]
Wennergren 1997
-0.693147
0.21979
Total (95% CI)
Heterogeneity: Chi² = 16.54, df = 8 (P = 0.04); I² = 52%
Test for overall effect: Z = 4.80 (P < 0.00001)
IV, Fixed, 95% CI
0.01
0.1
1
10
100
Favors Breastfeeding Favors Not Breastfeeding
Room sharing
Yes
No
Scragg et al, Lancet 1995
Room sharing last sleep but not bed sharing
Percent
exposed
Univariate
Multivariate
OR (95% CI)
Author
Country
Case
Control
Scragg (1996)
New
Zealand
20.7
37.1
0.44
0.25
Blair (1999)
England
25.3
39.0
0.53
0.51
Hauck (2003)
United
States
20.8
28.1
0.67
Not
reported
Carpenter
(2004)
Europe
28.0
44.5
0.49
0.32
Tappin (2005)
Scotland
35.8
63.5
0.32
0.31
Conclusion
Room sharing providing the infant is not bed sharing
decreases the risk of SIDS 3-fold.
Recommendation
Parent/s should sleep in the same room as baby for
first six months.
Definition of co-sleeping and bed sharing
• Co-sleeping and bed sharing were synonymous,
however the advocates of co-sleeping have
broadened the term to include parents and infants
sleeping in close proximity (e.g. room sharing but not
bed sharing). Accordingly, this term should be
avoided.
• Bed sharing is defined as the parent sleeping with
the infant on the same sleeping surface (usually a
mattress). A key feature is that the parent is asleep.
Bed sharing in the New Zealand case-control
study (1987-1990)
.
Cases
Controls
OR
Yes
24.0
10.5
2.7 (2.0, 3.6)
No
76.0
89.5
1.0
Mitchell et al, 1992
Confirmation that bed sharing is a risk for SIDS
SIDS
Vennemann et al, J Pediatrics, 2012
Interaction between maternal smoking and
infant bed sharing
Mother
smoked
No
Yes
No
Yes
Bed
sharing
No
No
Yes
Yes
(Expected
Scragg et al, BMJ 1993
Last two
weeks
1.0
1.4
1.7
3.9
2.4
Last
sleep
1.0
1.5
1.0
4.6
1.5)
Meta-analysis of bed sharing and risk of SIDS
by maternal smoking status
Bed sharing infants who were placed back in
their own cot to sleep
• Are not at increased risk (CESDI, Irish)
• However, mothers may intend to place their
infant back in own cot, but fall asleep. This
may account for why tired mothers and SIDS
cases unaccustomed to bed sharing appear
to be at higher risk.
• This provides strong evidence that bed
sharing is the problem, and not just the
characteristics of the families that bed share.
ORs (log scale) for SIDS and 95% CIs of bed-sharing by infant
age and mother smoking or not during pregnancy
Carpenter et al, Lancet, 2004
Bed sharing when parents do not smoke: Is
there a risk of SIDS?
Bob Carpenter et al, BMJ Open 2013)
• Combined data from 5 case-control studies
• ECAS (excluding CESDI), 1992 to1996
• Scottish 1996–2000
• New Zealand 1987–1990
• Irish 1994 to 2003
• GeSID 1999 to 2003
• 1472 cases and 4679 controls
Odds Ratios log scale
Bed Sharing Odds Ratios by age
for Breast Fed infants
when neither parent or both parents smoke
Estimated ORs
95%CI
Estimated SIDS rate per 1000 live births for selected
groups (mother 26-30yrs, 2nd child, birthweight 2500-3499g;
SIDS rate=0.5/1000)
Risk factor present
Feeding
Smoking
Room but not Bed
bed sharing
sharing
Ratio of
rates
Breast
None
0.08
0.23
2.7
Bottle
None
0.13
0.34
2.7
Breast
Mother
0.13
1.27
9.7
Breast
Both parents
0.24
1.88
7.7
Bottle
Both parents
plus alcohol
1.77
27.5
16.0
If parents follow our SIDS prevention messages the SIDS rate is very low.
If they bed share but otherwise do the right things the risk is increased
almost 3 fold.
The combination of parental smoking, bed sharing AND alcohol is lethal
(2.8/100).
If you add other factors the risk becomes even higher:
•
•
•
•
•
•
•
Birthweight of 2.25.kg
Mother aged 18 years
Maternal smoker
Partner smokes
2+ units of alcohol
Bottle feeding
Bed sharing
Risk >100/1000, i.e. 10%
The role of alcohol in New Zealand
• Review of all infant deaths referred to the coroner in the
Auckland region, 2000-2009
• Reviewed police records
• Total of 188 sudden unexpected deaths in infancy (SUDI)
• 121 occurred while bed sharing = 64%
• Alcohol was implicated in 17 = 14% of bed sharing deaths
Hutchison et al, Acta Paediatrica, 2011
Could maternal obesity (+/- sagging mattress)
increase the risk?
Conclusions 1: Bed sharing and SIDS
• There is no risk from bed sharing if the mother stays
awake.
• Bed sharing infants placed back in their cot are not at
increased risk of SIDS.
• The risk of SIDS with bed sharing is high when the mother
smokes or smoked in pregnancy.
• Maternal alcohol increases the risk.
• Maternal obesity increases the risk.
• There is a small increased risk when the mother does not
smoke in infants <3 months of age.
Conclusions 2: Bed sharing and SIDS
• Bed sharing is associated with a longer duration of
breastfeeding, but the effect is small
• There is no evidence that bed sharing is protective
against SIDS in any group
• The only group shown NOT to be at increased risk is
infants 3+ months of age, not preterm or low birthweight,
with non-smoking parents and no parental alcohol or
recreational drugs use and not sleeping on a sofa
Why is this issue important
• Although SIDS has dropped dramatically, SUDI continues
to be the major cause of death in the postneonatal age
group. For most countries the SUDI rate is around
0.5/1000 live births (SIDS 0.25/1000), but 1.1/1000 in NZ
• 50-70% of SUDIs are occurring in a bed sharing
environment, and this reaches 90+% in the first month of
life. (In a 10 year review in Auckland 64% were bed
sharing and this was 92% in those less than one month of
age.)
What might be done?
1. Parents have the right to know
2. Modelling appropriate infant care practices in
obstetric units is vital.
3. CYMRC is emphasising that the mechanism is likely
to be due to suffocation. Suffocation is clearly
preventable.
4. CYMRC is supporting the use of wahakura and pepipods.
5. Community advertising should be considered.
Definition of Sudden Unexpected Death in Infancy
• Not an ICD code
•
•
•
•
•
Seen through the eyes of the caregiver
Under 1 year
Excludes major external force e.g. motor vehicle
Unexpected Death usually in Sleep
Death without caregivers being alerted to a problem
Includes
Suffocation in bed, wedged, face covered, overlain
Unrecognised illness, e.g. infectious, metabolic, cardiac
SIDS (no cause after complete assessment)
Unascertained
Sudden Unexpected Death in Infancy
• 60-70 SUDI per year
• Many preventable
• A public health emergency?!
• Good news 3,000 babies have not died since 1992
• Disappeared off nation’s radar?
• “Among the industrialized nations, New Zealand has the
highest rate 1.1/1000”
• Maori 2.3, Pacific 1.3, Other 0.5 (per 1000 live births)
SUDI and bed sharing, 2003-2007
Number of deaths = 359
Bed sharing status unknown = 101
Bed sharing
Not bed sharing
154 (60%)
104 (40%)
Why do infants sleep in unsafe places?
• lack of awareness
• infant unsettled
o
moved to unsafe space
• no safe arrangement available
o
no cot, too cold, over crowded
• make shift arrangements
o
social gathering, away from home, decorating
• parental intoxication
Suffocation or Strangulation in Bed
• Entrapment/wedging
o
o
o
o
Soft surfaces, bedding poor fitting, bed/wall
Broken cots
Sofa, pillows and cushions
Domestic chaos
• Overlaying
o
Adult > sibling > mother while feeding
• Infants 20 times more likely to suffocate in adult bed than
in a cot or bassinette
• Hazards away from home and make shift
Own Sleep Space
• Risk from bed sharing increased by
•
•
•
•
Smoke exposure
Infant preterm or low birth weight
Under 3 months old
If others in the sleep space difficult to rouse e.g. alcohol, drugs,
medicines, toddlers.
• Sofa sleeping
• Parents have a right to know risks of bed sharing
• Own sleep space essential if others risks cluster
The CYMRC recommends that the Commission
should:
Support DHBs in developing quality improvement
systems that promote evidence-based safe sleeping
practices for infants, which are modelled in every
DHB and supported by clear policy and audit
systems.
A network across DHBs should provide clear national
guidance, reduce duplication and minimise variation,
while also supporting local participation in training
and development of safe sleep practices.
Needs Assessment
• Starts before birth
• Highlights where extra support needed
• Environmental risks
• Infant factors
• Plan documents how needs will be met
• Parents fully informed as of right
• Make good choices easy
Support Families
• Systems to get a space for baby to sleep
•
•
•
•
•
Heating to ensure warm
Reduce overcrowding
Wahakura
Pepi Pod
Cot rental system?
• Anticipatory guidance to plan for night time waking
management and feeds
• Modeling safe sleep in hospital
Pepi Pod
Wahakura
Risk Communication
• Low correlation between a risk’s
• “hazard” (how much harm it’s likely to do) and its
• “outrage” (how upset it’s likely to make people)
• Disempowering
• SIDS – unexplained can happen to anyone
• Empowering
• Suffocation and Strangulation – preventable
New focus of Suffocation and Strangulation
FINAL CONCLUSIONS
• The MoH recommendations on Safe Sleep are
evidence based.
• SIDS or SUDI are preventable
• Application of what we currently know could eliminate
SIDS (reduce it to 5-6 deaths per annum)
• The challenge is to find ways of implementing our
knowledge, especially finding ways to safely bed
share.
Pacifiers and risk of SIDS
Mitchell, Blair, L’Hoir. Pediatrics 2006
Mitchell
1987-90
New Zealand
0.43
Fleming
1993-95
UK
0.41
L’Hoir
1995-96
Netherlands
0.19
Hauck
1993-96
USA
0.33
Brooke
1996-99
Scotland
0.33
McGarvey
1994-98
Ireland
0.10
Carpenter
1992-96
Europe
0.44
Vennemann
1998-2001
Germany
0.39
The AAP task force recommends use of a
pacifier throughout the first year of life
according to the following procedures:
• The pacifier should be used when placing the infant
down for sleep and not be reinserted once the infant
falls asleep. If the infant refuses the pacifier, he or
she should not be forced to take it.
• Pacifiers should not be coated in any sweet solution.
• Pacifiers should be cleaned often and replaced
regularly.
• For breastfed infants, delay pacifier introduction until
1 month of age to ensure that breastfeeding is firmly
established.
Other possible health effects of pacifier
Disadvantages
• Increased otitis media
• Increased dental malocclusion
• Decrease in duration of breastfeeding
Advantages
• Decrease in dental malocclusion from finger
sucking
• Reduction in GE reflux
• Reduction in behavioural distress
Possible mechanisms
•
•
•
•
Reduction in infant face down
Reduction in GE reflux
Increased arousal
Improved airway
Recommendations
• The evidence is consistent and moderately strong.
• The possible detrimental effects have to be balanced
against the low risk of SIDS.
• Some countries are now recommending pacifier use, at
least in bottle fed infants.
• Pacifiers should no longer be discouraged, but not
specifically encouraged.
Head covering
10 studies with control data
Prevalence in SIDS was 24.6% vs. 3.2% in controls
Pooled unadjusted OR = 9.6 (95% CI = 7.9-11.7)
Pooled adjusted OR = 16.9 (95% CI = 12.6-22.7)
Population attributable risk = 27.1%
Blair et al, Arch Dis Child 2008
Figure 1 Forest plot of unadjusted odds ratio (and 95% CI) for infants found
with head covered by bedclothes after last sleep.
Blair, P S et al. Arch Dis Child 2008;93:778-783
Copyright ©2008 BMJ Publishing Group Ltd.
Recommendation
• In UK the “Feet to foot” campaign advised parents to
place the feet of the infant at the foot of the cot to
prevent head covering (1997).
• This advice was endorsed by the American Academy
of Pediatrics (2000).
• Although intuitively sensible there is no evidence that
it reduces risk of head covering or lowers risk of
SIDS.
Sleeping sack
In The Netherlands the use of the infant sleeping sack
is common.
L’Hoir et al showed in 1998 (Eur J Pediatr) that the
sleeping sack was associated with a lower risk of SIDS
Its use might prevent (1) head covering, (2) turning to
the prone sleeping position, and (3) thermal stress
Case
Control
OR
No
63%
25%
1.0
Yes
37%
75%
0.3
Immunizations
• The anti-immunisation lobby have postulated that
immunisations cause SIDS.
• However, immunizations are associated with a reduced
risk of SIDS (possibly because children that are being
immunized are well). Pooled OR=0.59 (0.53-0.66)