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Some Facts About SIDS

  • How common is SIDS? Over the past two decades the SIDS rate in Ireland has declined gradually from a high of 2.3 per 1000 live births (an average of 134 deaths per annum) in the 1980s to a low of 0.55 per 1,000 live births in 2004 (34 deaths). This represents a drop of 76% and is attributed largely to the introduction of advice to parents/carers to place infants to sleep on their backs (Back to Sleep campaign). However, despite the reduction in the number of cases, SIDS remains the leading cause of death in infants in the postneonatal period (four weeks to one year).

  • Age Distribution The majority of cases (70%) occur between the ages of 28 days and six months, with the greatest number occurring in the 2-4month age group. However, every year a proportion of the cases which occur in Ireland are outside the average age range with between 4-6% over one year of age.

  • Gender Distribution More males than females are affected (1.5:1). While there is a greater preponderance of males vs females in many causes of infant mortality, most of these, unlike SIDS are restricted to the perinatal period. The reason for the excess in male deaths is not known.

  • Does SIDS only occur in cots? SIDS can occur anywhere an infant is sleeping. While the majority of cases occur during the night-time sleep in the infants' home environment, in Ireland it has been known to occur in cars, creches, in the infant's mother's arms and even in hospitals.

  • Weekend Trend There is a weekend trend observed with more cases occurring on Saturdays and Sundays. This weekend trend has been observed internationally and it has been speculated that it may be a consequence of changes in environment or routine during this time.

  • Seasonal Distribution Throughout the 1980ís, the international epidemiology of SIDS showed a predominance of cases occurring in the coldest months of the year. In Ireland there has been little or no seasonal variation since 1992.

  • Socioeconomic Factors SIDS affects infants from all socio-economic backgrounds but the incidence is higher amongst families of lower socioeconomic status.

  • Maternal Factors Research studies have demonstrated a strong correlation of SIDS with young maternal age and higher parity ie second and later born infants are at greater risk than first born babies. An increased risk has also been observed for infants of single mothers.

  • Obstetric Factors Research has consistently shown that infants born prematurely and/or of low birthweight are at increased risk of SIDS and rates vary among different ethnic groups.

  • Lifestyle Factors:
  • 1: Exposure to Tobacco Smoke: Exposure to tobacco smoke significantly increases an infantís risk of SIDS. Maternal smoking during pregnancy is now considered the most important risk factor for SIDS along with use of the prone sleeping position (placing infants to sleep on their tummies). This risk is increased proportionally as the number of cigarettes smoked is increased. The increased risk is not restricted to the mother smoking during pregnancy however and there is also an effect of second hand or environmental smoke as evident from the observation that the SIDS risk increases as the number of smokers living in the household increases. Babies should be kept in a smoke free environment at all times. 2: Sleep Position: There is clear evidence that infants who sleep on their tummies are at a higher risk of SIDS. Place the baby to sleep on their backs at all times. There is no evidence that this increases the risk of choking or vomiting. When babies are older and capable of rolling from back to front and back again, let them find their own position but at the start of every sleep time, put him/her on their back. Placing babies on their sides to sleep also carries an increased risk due to the likelihood of the baby rolling into the prone (stomach) position during sleep. Proposed mechanisms whereby prone sleeping could increase the SIDS risk include airway obstruction, impairment of arousal and swallowing reflexes and overheating. The risk is potentiated by use of soft bedding, swaddling of infants and minor illness.In addition to prone sleeping, use of the side position for sleep also appears to be less safe than placing babies on their backs. It is thought that this may be due to the possibility of the infant rolling onto their front. 3: Overheating Overheating, possibly by interfering with the central nervous system control of breathing, is another risk factor for SIDS. When sleeping, babies can overheat because of too much bedding, clothing or because the room is too hot. If baby's tummy feels hot or if he/she is sweating anywhere then he/she is too hot. Babies do not require hot rooms to sleep in. Sheets and lightweight blankets are best as they make it easiest to adjust the temperature by being readily removed/added. In warm weather it may not be necessary to have any bed coverings at all. Do not use duvets, quilts or pillows. The cot/pram/bed should never be placed next to a radiator, heater or fire, or in direct sunshine. Sleeping on their backs leaves an infant's face and internal organs exposed so that they can radiate heat more readily.

    4: Head covering and use of Soft Bedding A primary site for heat loss is through the head and thus head covering with bedding may lead to overheating. Front- sleeping babies are more likely to slip down under the covers than those sleeping on their backs. Hats and additional clothing should be removed as soon as an infant is brought indoors. To prevent infants from wriggling down under the covers place them to sleep with feet to the foot of the cot, basket or pram with covers below the shoulders. Covers should be tucked in loosely and ensure they cannot slip over babyís head. Soft bedding such as pillows, quilts and duvets should not be used in the infant's sleeping area. The mattress should be clean, firm and fit the cot appropriately so that there is no entrapment hazard presented by a gap between the mattress and the edge of the cot.

    5: Room sharing Babies who sleep in a cot in their parents' bedroom are less at risk than if they are on their own in a separate room. The baby's cot should be placed in the parent/guardian's own bedroom for the first six months.
    6: Bed-sharing Do not bed-share with your baby if you smoke, are under the influence of alcohol or other drugs or medication or you are excessively tired. While earlier studies on bedsharing and SIDS have reported that bed-sharing was not a risk factor for infants whose mothers did not smoke, more recent studies have indicated that even among nonsmokers bedsharing increases the SIDS risk for babies less than eleven or eight weeks of age suggesting that all forms of bed-sharing should be avoided for these infants. Never sleep with your baby on a sofa or armchair.
    7: Infant Wellbeing Research on the role of infectious illness in SIDS have concluded that illness may interact with other factors such as overheating or prone sleeping to increase an infant's risk of SIDS. Data from the UK revealed that SIDS infants have a range of symptoms which appear to be of a general nature and not related to any one system. Symptoms are seen throughout life and not related to the time of death.

  • What causes SIDS? Despite the identification of a number of risk factors, no single cause of SIDS has been identified. Death occurs quickly and quietly during sleep and there is usually no sign of a struggle.

  • Can SIDS be prevented? Until we have established what the cause of SIDS is we cannot ensure its prevention. However, a number of steps can be taken to reduce an infant's risk of SIDS as much as possible:
  • 1. Place babies to sleep on their backs.
    2. Keep baby in a smoke free environment at all times.
    3. Ensure that baby does not become too hot.
    4. Keep baby in the feet to foot position with head uncovered.
    5. The safest place for your baby to sleep is in their own cot in the parent's bedroom fo the first six months of life.
    6. If baby is unwell seek medical advice promptly.
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