Despite several positive trends, rates remain unchanged and the proportion of deaths associated with direct bed sharing is increasing, according to new data.
The rise in vaping may help explain why sudden unexpected death in infancy (SUDI) rates in New Zealand have plateaued despite declines in some risk factors, researchers have found.
“Despite decreases in NZ of infant prone sleeping and maternal smoking in pregnancy, SUDI mortality has not declined in the last decade. This suggests that new or increasing risk factors are contributing, or existing ones are becoming more prevalent and/or impactful,” they wrote.
Using coronial data, researchers identified 101 SUDI cases in NZ in 2022-2023, which detailed sleep environment, feeding and parental smoking and vaping behaviours.
The overall SUDI rate was 0.87 per 1000 live births, with markedly higher rates among Maori (1.97 per 1000) and Pacific (0.91 per 1000) infants compared with European infants (0.17 per 1000). Most deaths (63.4%) occurred in infants younger than 13 weeks, and 72.3% occurred during direct bed sharing.
Maternal smoking was reported in 51.5% of cases, vaping in 30.3% and either smoking or vaping in 72.7%. Vaping was significantly more common in bed-sharing deaths than non-bed-sharing deaths, and infants who died while bed sharing were much more likely to have been exposed to nicotine through maternal smoking or vaping.
Compared with earlier New Zealand data, covering 1987-1990 and 2012-15, several risk factors had shifted by 2022-23, including a continued increase in the frequency of bed sharing – from 24% to 57.5% to 72.3%.
“The proportion of deaths associated with direct bed sharing is striking and is increasing. Vaping appears to be an emerging SUDI risk factor, especially when combined with direct bed sharing,” the authors wrote.
“The consistency and strength of the observed associations support the hypothesis that smoking and vaping are markers of unsafe-sleep contexts, including bed sharing, and reinforce public health messages advising against bed sharing in the presence of any nicotine exposure.”
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The researchers suggested that modifying sleep practices could have a substantial impact.
“If all mothers who smoked or vaped used in-bed sleepers instead of direct bed sharing, about 45% of SUDI deaths in this series might have been prevented, assuming sleepers offer protection comparable with separate sleep surfaces,” they wrote
There was a significant increase in the proportion of Maori (from 48.8% to 49.6% to 68.3%) and Pacific (from 6.4% to 15% to 17.8%) infants among SUDI cases across these datapoints, as well as a rising trend in maternal age – 17.6% of SUDI cases were with mothers aged at least 30, which increased to 20.3% and then 37.9%.
“Encouragingly, several trends are positive. Fewer deaths now occur among young mothers, and prone or side sleeping has declined, reflecting successful safe-sleep campaigns,” authors wrote.
“Breastfeeding rates among cases remain high, a recognised protective factor against SIDS. Also, maternal smoking at 2 weeks postnatal has fallen markedly from 13.7% in 2009 to 7.3% in 2021.”
In 2022, there were 117 SUDI deaths across Australia, a roughly 80% reduction since 1989. Rates in First Nations families are 3-4 times higher than non-Indigenous families.
Vaping has been promoted as a safer alternative to smoking, and more than one in 10 NZ adults reported vaping in 2023-24.
“Public education endorsed by the Royal College of Midwives (RCM) in 2019 stated that nicotine alone is relatively harmless and reiterated this in 2022. Yet nicotine crosses the placenta, reduces foetal blood flow and lowers birthweight. We suspect that vaping may also produce the same infant ‘arousal defect’ seen with tobacco exposure. Public-health messaging should urgently reflect these risks,” the authors wrote.
They said the findings highlighted a concerning stagnation in SUDI outcomes alongside widening inequities and the increased prevalence of vaping.
