It is often stated by parents and grandparents, ‘I slept on my tummy and I slept my babies on their tummies and they were fine’ or ‘I smoked around my babies and they are all grown up and ok – they didn’t die of SIDS!’ This is thought to be due to reduced arousal responses. However, arousal and swallowing mechanisms are needed to protect baby’s airway and work best when a baby is placed to sleep on the back.
Although many studies have identified underlying risk factors for SUDI, the causative or pathophysiological mechanism that make some babies more vulnerable than others still remains uncertain. However, it is currently widely believed that SIDS is multifactorial. The Triple Risk Model (Figure 1) is useful for understanding why SIDS may occur with particular babies and why it is important to follow the Red Nose safe sleeping practices when caring for every baby. This model suggests there are three interacting factors: when all three are present, SIDS is more likely to occur.
What are these three factors?
1. Vulnerable Baby
The first significant factor of the triple risk model represents a baby with an underlying weakness or abnormality which may only become apparent when the baby is exposed to stress. Theories that have been extensively studied include brain pathways, control of breathing or heart rate, genetic factor(s), or problems with the baby’s arousal(12,13).(14) Often the studies focus on babies born pre-term, or of low birth weight, or who were exposed to tobacco smoke or illicit drugs during the pregnancy because these babies are known to experience a higher rate of SUDI(15).
2. Critical Development Period
The second factor of this model refers to the critical and vulnerable development period. Research has identified the critical developmental period as the baby’s first year, particularly the first 6 months of life, with the peak at 2-4 months of age. During this critical developmental period, babies are growing and developing rapidly, with many changes occurring in homeostatic controls. The age distribution for SIDS shows that 90% of deaths occur in the first 6 months of life, with a peak at 2-4 months, and few babies dying in the first month or at older ages.(16)
3. Exposure to an External Stressor
The third factor of this model involves the exposure of the baby to an outside stressor that may include known risk factors such as tobacco smoke, tummy or side sleeping position, overheating, head covering or an upper respiratory infection or illness. Most babies can experience these conditions and survive, but a vulnerable baby may not be able to overcome them during their critical period of development. The triple risk model explains that most babies can experience these stressors but still survive.
The Triple Risk Model proposes that a vulnerable baby, at a critical period of their development, is exposed to a stressor with which he or she is unable to cope. According to the triple risk model, SIDS does not depend, therefore, on one independent cause but may occur if there is an interaction of these three factors/circles occurring simultaneously. If you can remove one of the three interacting factors, SIDS is unlikely to occur.
There are some factors that we cannot change such as the age of the baby (critical period of development) or identify which babies may have an underlying vulnerability.
Our Safe Sleeping recommendations focus on taking action where it is possible and removing as many risk factors as possible from a baby’s environment during their critical first year of life. We have to assume that all babies are vulnerable and ensure Safe Sleeping strategies are used for every sleep.
Last modified: 17/05/23
Last modified: 17/5/23