When a seemingly healthy baby dies suddenly, and after a post-mortem is performed no obvious cause can be found, a verdict of Sudden Infant Death Syndrome (SIDS) may be recorded. It is commonly referred to as Cot Death, usually because the baby is found in his or her cot. Although for the most part this is the case, babies have died while in their pushchairs and even, more rarely, in their parents arms. Sudden Infant Death is the most common cause of death in babies under one-year-old.

What Do We know?

The fact that we have such technology and knowledge available, and yet we still cannot find any one recurring factor in these deaths, can seem quite remarkable. There are, however, several known factors that relate to a great many of these deaths. These factors, and the statistical evidence drawn from them, show that certain children are more at risk from SIDS. Factors that are known to increase instances of SID include:

• Living conditions - Children born to families who live in difficult circumstances. Factors include poverty, poor housing, and over-crowding.

• Baby gender - It is a statistical fact that there are more male victims than there are female, even when the boy to girl birth ratio has been accounted for. No reasonable explanation can be offered for this.

• Baby age - Babies that are under six months old, with a peak at the age of 2/3 months. This may be due to maturity, but again there is no real explanation.

• Birth difficulties - Premature or low birth weight babies.

• Subsequent children - A child born to parents who have children already, are also more likely to be victims.

• Cold Weather - Children that are at the peak ages during colder months are more susceptible. This factor seems to be on a decline.

Fortunately, there isn't any evidence to suggest that if you have had one baby die unexpectedly, that you are more likely to have it occur again in subsequent children. It is also relatively rare in babies over one year old. Only approximately 3.7% of recent cases have been in children over the age of one.

Among the 'developed' countries, The Netherlands and Japan appear to have the lowest rates of SIDS. France, Norway, Sweden, and the UK, have rates a little higher. New Zealand, Australia, and the USA, have the highest rates. No one is really sure why one country should have more SIDs than another. Asian families tend to have the lowest occurrence of SIDs than any other. However, again, there is no real explanation for why this is the case.

What Can be Done?

The rate of Sudden Infant Death is statistically on the decline. The introduction of public awareness campaigns in many countries may be a contributing factor to this change. New and prospective parents are now given advice on some both the dos and don'ts of baby-care to help them reduce the risk of SID. Basic advice usually suggests:

• Place your baby on his/her back for sleep, and with their feet at the foot of the cot. This is intended to stop your baby wriggling down under the covers.

• Don't let your baby get too hot. Many parents will wrap their baby in thick blankets, but if you're normally in a fairly warm environment, this is not necessary.

• Don't let your baby sleep in your bed. Your baby can get too warm in your bed.

• Quit smoking during pregnancy. This advice includes avoiding passive smoke intake, where practical, and therefore goes for fathers too. In addition, if you take your baby to visit any household that includes smokers, make sure they don't smoke in the same room and if possible not even in the house.

• Keep your baby's cot in your room for at least 6 months. No one is sure why this should be a factor, but is does seem to help reduce the risk.

How can SID Effect Families?

When parents have a SID occur they can find themselves troubled by a spectrum of emotions and feelings:

• Guilt - Asking themselves if they did something wrong. In the majority of cases there is nothing that the parents could have done to prevent it from happening, but the feeling can still remain that it was something that could have been prevented.

• Anger - Finding that they are asking 'Why us?' or 'Why my child?' is common. This is a natural reaction to such a situation and parents may feel angry for a long time. Talking to others who have been through the same can sometimes help.

• Curiosity - Basically a need to know more about what happened. It is only natural that parents, or indeed other relatives, find that they need to know more about SID, the causes, and research that is currently being carried out.

• Frustration - The fact that no one knows what causes these deaths to occur can be difficult for the bereaved to accept. Given the fact we have a fantastic array of medical and biological knowledge available to us today it seems wrong that there are no solid answers to why SID occurs.

Help for Families that Have Experienced SID

Firstly, there is the organisation FSID (Foundation for the Study of Infant Deaths). This is a UK-based registered charity. They issue a free newsletter that includes information on any new developments and new research ideas, as well as general awareness leaflets. The organisation also offers help to bereaved families, including a befriending scheme, where parents who have lost a child to SIDS can get in touch with others who have recently had a loss and offer advice and companionship. The organisation also arrange charity events and get-togethers, on a regular basis.

In the UK there is a scheme for parents who are having a child after a SID. The scheme is called CONI (Care Of the Next Infant). In the event of parents having another child after a SID, the scheme offers advice and reassurance, and the chance to have a pregnancy monitored more closely than it might otherwise be. After the child is born, weekly visits from a Health Visitor can be arranged. CONI also offer parents apnoea monitors. An apnoea monitor monitors a child's breathing while they are asleep, and if the child stops breathing an alarm will sound, usually after 20 seconds. Once the alarm has sounded parents are then advised to stimulate the child, say by tickling its foot. Additionally parents may be given a 'diary' to record incidents of apnoea alarm alerts. The parents can record the alarms occurrences and other information, such as whether the alarm was due to the monitor being faulty. The gathered information can assist in tracking the effectiveness of the monitor and provide useful information in assisting ongoing support by the organisation. When parents feel they don't need to use the monitor any longer, they give it back to be used by someone else.

What Next?

There are many research projects currently going on. Various factors are being thoroughly investigated to test their relevance and validity. Apart from the possible causes mentioned already, other areas of study include:

• Airway functions in low birth weight infants

• How physiological control mechanisms are influenced by age, sleep positions, and passive smoke¹.

• Recent research carried out offers a theory that cells found in a small part of the child's brain stem may be defective. Apparently these cells have a defect that prevent the child's autonomic functions from detecting dangerously high levels of carbon dioxide in his or her system².

Ultimately, we are still no nearer to finding out what the exact causes of Sudden Infant Death are, but progress in finding possible means to reduce the risk is being made.