A Better Start National Science Challenge and Whānau Āwhina Plunket recently held a webinar, Sleep Me Safe, which explored the latest research and developments in Sudden Unexpected Death in Infancy (SUDI), including results from the most recent NZ case-control study.

A Better Start Deputy Director Barry Taylor and Whānau Āwhina Plunket’s Chief Nurse Dr Jane O’Malley were joined by SUDI academic experts Emeritus Professor Ed Mitchell and Professor David Tipene-Leach for the webinar.

There were a large number of questions from the audience, which Ed Mitchell, David Tipene-Leach and Barry Taylor have answered below.

If you missed the webinar, you can watch it here

What is the link between maternal smoking and SUDI? Is there any direct link?
There is a very strong link between maternal smoking and SUDI. It is thought to be causal . Smoking reduces birthweight, which is associated with SUDI, but more importantly it affects the fetal brain and reduces arousal (waking up) if, for example, the airways are accidentally obstructed. – Ed

In this study did you only look at smoking in utero? Did you also look at smoke exposure postnatally?
Smoking in pregnancy is strongly associated with smoking postnatally, therefore it is hard to disentangle the two time periods. Smokers who quit when they know they are pregnant will often be smoking for the first 8 weeks of pregnancy. From a biological perspective it is likely the bigger effect is due to smoke exposure in utero. However, in the original New Zealand Cot Death Study there was a very small effect from father’s smoking where the mother was a non-smoker, suggesting there is a postnatal effect but much smaller than that resulting from the mothers smoking. – Ed

If a mother stops smoking during pregnancy, does this reduce the risk?
Yes. Quitting completely during pregnancy is better than reduction in amount smoked. Ideally women should stop smoking before they conceive. – Ed

What if a mum didn’t smoke during her pregnancy but does smoke postnatally? Is that included in maternal smoking?
In our study we used smoking in pregnancy thus mothers who only smoked postnatally would be treated as no smoking in pregnancy. Probably this is too conservative, as mothers who claim they didn’t smoke in pregnancy but recommenced after the birth, probably stopped as soon as they knew they were pregnant, and damage to the developing fetal brain may have already occurred. Our approach would reduce the risk, so the risk might really be even higher! – Ed

Is the risk of SIDS also increased with more people who are now vaping?
There is no data on vaping and SUDI. Vaping with nicotine may be less risky than smoking tobacco, but nicotine is known to reduce blood flow to the uterus, so it is not recommended. – Ed

Was there a reason smoking wasn’t tackled if both parents smoking had an impact?
The wahakura plan was a way to tackle bedsharing where there was smoking in pregnancy without stopping smoking because it was thought to be so difficult to do. We (Māori SIDS Prevention Programme) did try to find creative ways to do smoking cessation but we simply didn’t have the resource of influence to effect anything big. – David

Have you talked about the risks of sleeping prone but no smoking and no bed sharing?
Prone sleeping position is a risk under any circumstances and should be avoided throughout the first year of life or until the infant has developed the motor skills to determine their own sleep position. – Ed

What other variables have been looked at in the bedsharing deaths? E.g. maternal alcohol, breastfeeding rates, pillows/blankets around etc.
Maternal alcohol and drug use in the previous 24 hours are associated with SUDI when bed sharing. Breastfeeding reduces the risk of SUDI, but even if bed sharing increases breastfeeding, this does not outweigh the increased risk from bed sharing. In the UK for ‘safer’ bed sharing the Lullaby Trust and their advisers recommend no pillows or blankets even for the parents when bed sharing. Can you imagine that in New Zealand in winter in the poor families at higher risk? They’d risk hypothermia! – Ed

Has mode of feeding been considered? Breastfeeding vs formula/bottle feeding when bed sharing?
Breastfeeding is associated with a lower risk of SUDI than infants fed formula. Breastfeeding doesn’t outweigh the increased risk from bed sharing. The risks are independent of each other. Breastfeeding halves the risk, but bed sharing increases the risk 5-fold. For mothers who smoke, breastfeeding and bed sharing increases the risk approximately 15-fold. – Ed

How many of the deaths could have been prevented if the families had been taught to safely bedshare?
One of the goals of the study was to identify ways in which mothers could safely bed share. There were no circumstances where bed sharing is safer than sleeping in a cot
However, there is no significant increased risk if all the following apply:
• Baby is older than 13 weeks of age
• Baby was not born preterm or low birth weight
• Mother did not smoke in pregnancy
• Mother has not taken alcohol or drugs in the previous 24 hours
• Sleeping is not on a sofa/couch
It should be noted that if mother/baby are doing all the right things (i.e. breastfed, term infant with good birthweight, mother non-smoker, doesn’t take alcohol or drugs, baby sleep on back, in the parental bedroom and doesn’t bed share with baby), then the risk of SUDI is very low. Although bed sharing in these circumstances increases the risk 5-fold, the absolute risk is still low. This is where the SUDI risk calculator is very useful to have an informed discussion with the mother.
I support the use of wahakura and pepi-pod for ‘safer’ bed sharing. – Ed

Carol Barber’s recent Rockabye baby study demonstrates that co-sleeping is common in NZ. It is a cultural norm. I suspect we are fighting an uphill battle. Is it time to move to a harm minimisation approach? Empower families with the knowledge to safely co-sleep rather than deny them the knowledge?
This is exactly what we think the wahakura does – that is – it is a way of championing the idea that there are safer ways to bedshare. The success of the wahakura is twofold: 1) that it is a method of bedsharing that is safer than direct bedsharing 2) that it has certain attributes that make it attractive to Māori women who for whatever reason bedshare more frequently and more habitually. – David

Can you talk more about bed sharing and define this a little further? Were both parents in the bed, where was the baby positioned – in the middle or side, what type/size of bed, were blankets being shared?
Definition of bed sharing is parent/caregiver sleeping with baby on the same sleeping surface. 95% of deaths are associated with the sleeping mother. Addition of another adult doesn’t appear to increase the risk further, probably because the baby in on the outside and away from father. Having other children in the bed is high risk, probably because they are even less aware of baby than the mother. – Ed

Was bed sharing defined as ever bedsharing, occasional bedsharing or planned bedsharing?
In the study bed sharing was at the time of death (cases) or nominated time (controls). We didn’t ask whether the mother unintentionally fell asleep, although for the description of the events this clearly did occur. We do know that there is an increasing risk with duration of usual bed sharing (no bed sharing (lowest risk), less than 2 hours, 2 to 5 hours and 5+ hours (highest risk). – Ed

Were the bedsharing deaths in families that were habitual bedsharers or were they one off episodes relating to exhaustion / infant illness / as a last resort?
A mixture of all of the above. However, symptoms of illness are no more common in bed sharing infants than those sleeping in a cot, so I don’t believe it’s a major risk factor. Exhaustion? I’m not sure. It’s very difficult to quantify retrospectively, and what mother is not exhausted when she is waking frequently to feed baby. However, the commonest story we hear is that the mother fell asleep while breastfeeding. But is that not surprising when lying down at night? It is safer at night to get up and feed baby in a chair, as mothers do during the day. I have suggested that if mothers are going to take a baby to bed with them for feeding it might be safer to put the alarm/timer on to wake them if they inadvertently fall asleep. But I have no evidence that it would work! – Ed

Co-sleeping is quite normal in Asian countries, why are their SUDI rates much less than NZ rates?
You are absolutely correct. The best studies have come from Hong Kong and from studies of Bangladeshis in England. Although bed sharing is common, the mothers very rarely smoke. The fathers smoke, but not in the home. There are other practices that are different. Fathers are often banished to the spare bedroom or couch! And often the grandmother comes and stays and takes over running the house. The mothers only task is to look after baby for the first few months of life. – Ed

Most continue to bedshare, no matter what way you say it. What else can be done?
I would recommend risk assessment. If the absolute risk is very low, that is the mother is following all the other recommendations and baby is low risk, then bed sharing is only going to increase the risk from very low to low. The low-risk family wouldn’t qualify for a wahakura or pepi-pod. So advise having a cot beside the bed. However, if the baby is a high risk due to maternal smoking etc, then supply a wahakura or pepi-pod and educate. – Ed

What percentage of SUDI deaths in bedsharing context were babies in a pepi-pod or wahakura?
Very few. The bigger problem is that the pepi-pod or wahakura was not being used at the time of death. – Ed

The wahakura is amazing but I find that there isn’t enough funding or how to weave them for our families that need them. For instance, to meet the criteria the parent must be smoking. So the rest that bedshare continue to do so. Also they grow out of them so quickly, so then struggle to find our families cots.
Yes they are amazing! Yes funding is restrictive. So, smoking becomes the reason to receive one. I would say those infants whose mothers don’t smoke (unless they are otherwise ill) don’t need a wahakura/pepi-pod device as their risk of SUDI is very low. Growing out of them is also a factor – but the high risk period is in the younger months. The wahakura strategy doesn’t have an answer to everything. – David

Māori and PI babies often grow out of pepi-pods at an earlier age than what might be ideal – what consideration has been made of this? Could a larger pepi-pod be designed?
Possibly, but as the risk from bed sharing is highest in the youngest infants, this is where the focus should be. Indeed I know people have advocated for smaller pepi-pods for use in postnatal wards and neonatal units as the standard pepi-pod is too big for the hospital bed, which also has to accommodate the sleeping mother. – Ed

Are soft sided pepi-pods as effective as ones made from more structured/hard materials?
It depends on how soft the sides are. The side should be strong enough to withstand the mother rolling up against it. – Ed

As a lactation consultant, I worry about the number of women who give up breastfeeding because a baby refuses to stay asleep on a separate surface. They are convinced that formula is the answer to ‘better sleep’. Then we lose breastfeeding as a protective factor.
As a paediatrician I strongly advocate breastfeeding. Breastfeeding reduces the risk of SUDI, but even if bed sharing increases breastfeeding, this does not outweigh the increased risk from bed sharing. – Ed

I work with lots of families who use ‘nests’ for their babies to sleep in. While we advise against this, is there any evidence to support the increased risk of SUDI using these specific products?
Actually no. Our recent study (2012-15) was done before they became popular. The concern is that they may increase the risk of suffocation if the face gets pushed up against them. As the risk of SUDI is higher in poor families, it seems unlikely they could afford them (I saw online one advertised for AU$249). – Ed

Did the study include sleeping in a car seat risks?
No deaths occurred in a car seat. There are theoretic reasons why it might be a risk, so I certainly would not recommend leaving baby to sleep in the car seat. – Ed

I’m interested in the use of the SUDI calculator – is this available to use widely or just within the parameters of your study? As far as I am aware, this is only used at the moment in the Counties Manukau DHB. – Barry

Was age of baby and or age of mama/caregiver considered? Does SUDI feature more in one particular age group?
Age: SUDI is very rare in the first week of life. The peak incidence is 2-3 months then the numbers decrease steadily. By 6 months of age 85-90% of SUDI events have occurred. After 12 months of age there is less than 1 case a year. Maternal age: Highest in teen mothers, then decrease steadily with maternal age. – Ed

It would be interesting to know if the housing crisis contributed to the increased rate – in that it went up a bit from 2019?
The answer is ‘possibly’ – but how would one ever know? What is clear is that overcrowded housing most likely contributes greatly to difficulty in the provision of a safe sleep space. – David

What role do portacots play, given they are unstable, low-down close to a cold damp floor?
Portacots aren’t covered under the mandatory standard for household cots and should be used differently to household cots.
• They’re not as sturdy as regular cots and aren’t designed for constant use.
• It’s recommended that when a baby will be left unsupervised for regular sleep times and overnight, they should be in a cot or other sleeping environment that complies with an Australian New Zealand standard – in case the portacot collapses and injures baby.
• It is safer for baby to be in a portacot than bed sharing.
• The wahakura or pepi-pod is the answer here! – Ed

Tena koe David – fantastic work you are leading with Te Whare Pora. How many Māori women are able to access this support and is it spreading throughout Aotearoa?
Te Whare Pora is a new programme. We have only one in the country. Like the wahakura I imagine that we will have to ‘let it run’ for a while, write about it, gain some community support for this Kaupapa Māori antenatal initiative, get some researched outcomes and then tender in the public space for funding. I wonder if the Māori Health Authority will see things differently. – David

Fantastic to see the dramatic drop in Māori mortality rate in late 1990s – what helped facilitate this success?
Presumably mortality declined on the basis of reduced risk behaviours (although we don’t know this) and reduced risk behaviours (I would claim but have no evidence of) occurred on the back of a set of SIDS prevention messages that went through the Māori SIDS Prevention Team filter. Ie ‘control of the message’. – David

If you look carefully at the figure there was a decrease in both Māori and non-Māori SIDS, but the total rate did not change. That was a puzzle until I realised that it was caused by a change in definition of ethnicity. Let me explain: if one looked at SIDS mortality by ethnicity one has a gradient from non-Māori (lowest) to part-Māori (intermediate) and to Māori (highest). The change in definition moved part-Māori from the non-Māori category to Māori, which resulted in a reduced level of SIDS mortality for non-Māori (due to loss of a group with a higher mortality) AND a reduction in mortality for Māori (due to gaining a group with a lower mortality). But the overall rate didn’t change. – Ed

When will the SUDI provisional 2019/20 review be available?
This a Ministry of Health decision – hopefully this year! – Barry

Where can we see the full paper? Is it published or available yet?
Key papers are:

Mitchell EA, Thompson JM, Zuccollo J, MacFarlane M, Taylor B, Elder D, Stewart AW, Percival T, Baker N, McDonald GK, Lawton B, Schlaud M, Fleming P. The combination of bed sharing and maternal smoking leads to a greatly increased risk of sudden unexpected death in infancy: the New Zealand SUDI Nationwide Case Control Study. NZ Med J 2017; 130: 52-64.

MacFarlane M, Thompson JMD, Zuccollo J, McDonald G, Elder D, Stewart AW, Lawton B, Percival T, Baker N, Schlaud M, Fleming P, Taylor B, Mitchell EA. Smoking in pregnancy is a key factor for sudden infant death among Māori. Acta Paediatrica 2018; 107: 1924-31 doi: 10.1111/apa.14431

Carpenter R, McGarvey C, Mitchell EA, Tappin DM, Vennemann MM, Smuk M, Carpenter JR. Bed sharing when parents do not smoke: Is there a risk of SIDS? An individual level analysis of five major cases-control studies. BMJ Open 2013;3:e002299.

Our paper on ‘hazards’ should be published early 2022. – Ed

With regards to families who were considered to be well-informed re SIDS deaths, is that relating to awareness of the recommendations to sleeping babies supine on a solitary surface, or all associated risk factors including smoking, prematurity etc?
We assessed knowledge of key SIDS risk factors including smoking, prone sleeping and bedsharing. – Barry


Photo credit: Zelle Duda/Unsplash

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