As with so much 'baby gear', there's quite a choice when it comes to buying the right mattress for your baby; because of the choice, cots are rarely sold with a mattress.  Besides offering a comfortable sleep, choosing the right mattress is largely about reducing risk of harm to your baby.  Although your baby is most unlikely to come to harm whilst in their bed, there are precautions to be aware of to make that tiny chance even smaller still.

Even though you may prefer a soft mattress, babies need a firm one.  If a baby sinks into their mattress then they may struggle to turn over and move.  A firm mattress will also give them the support they need as their back and neck develops.

You must always buy a new mattress for your baby.  At one time, second-hand mattresses were thought to be a causal factor for Sudden Infant Death Syndrome (SIDS) or Cot Death.  The causes of SIDS are still largely disputed, but ensuring a new mattress for your baby is one precautionary measure that could just reduce that risk.  A new mattress will also be firm whereas one that's been used before may have become softer.

Ensure that the mattress fits snugly to the edges of the cot.  Cots come in standard sizes, as do the mattresses, but if you find that the mattress isn't a good fit, exchange it for a different one.  If the mattress doesn't fit to the edges of the cot then there is a risk that your baby could get caught between the cot and the mattress.  Although that sounds trivial, baby's aren't very agile in their early stages and becoming trapped in this way could lead to agitation, frustration and panic.

Mattresses are made from various materials and prices vary accordingly.  Don't assume that the most expensive mattress is the best - it's largely a matter of preference.  So long as each mattress displays the correct safety marques, it has been deemed safe to use; even the cheapest mattresses have to pass stringent safety checks in most countries.

A cotton cover is usually better than an artificial one because cotton allows the skin to breath properly.  Internally the mattress may be foam, sprung or fibre.  Foam is the cheapest option, usually providing a good firm surface.  Sprung and fibre mattresses 'breath' slightly better.

Hypoallergenic mattresses are good for babies who suffer, or may be at higher risk of, allergies.  If you have a history of allergies in your family, including food or animal allergies, hayfever or asthma, then paying a bit more for a hypoallergenic mattress offers a good precaution.  Hypoallergenic mattresses include a quilted top layer that can be washed at high temperature to kill dust mites that aggravate allergies.

Your newborn baby is going to spend a lot of time sleeping - make sure they're welcomed into the world with a good bed, but don't feel that you have to pay the earth to give them peaceful nights!

The number of babies being put to sleep on their backs - a sleep position considered the safest - has reached a plateau since 2001.  The Back To Sleep campaign launched in 1994 encouraged parents to place babies to sleep on their backs - rather than lying on their front.  It was discovered that this position resulted in less incidences of Infant Death Syndrome (commonly known as "cot death").

Cot Death is the sudden, unexpected death of a baby.  Even after a post mortem, the death remains unexplained.  It is referred to as Sudden Infant Death Syndrome (SIDS).

Do we know the causes?  Not really.  A single cause has not been named.  There could be various, even numerous factors that lead to the death, occurring when the babies are most vulnerable.

Are all babies at risk?  It seems so.  There is no evidence it happens to a certain race, or culture, or type of person.  It usually occurs when the baby is under 6 months and it can happen at any time - not just when the baby is in a cot.

Are baby boys or girls more prone?  It seems boys are slightly more at risk, as are premature babies and those of a low birth weight.

How can we reduce the risk?

• Put babies to sleep on their backs
• Do not smoke during pregnancy: you or your partner
• Don't allow anyone to smoke in the same room as your baby
• Consult your doctor if your baby shows any signs of illness
• Buy a new mattress for each baby, don't use second-hand mattresses
• Use a firm mattress but don't use a pillow
• Avoid cot bumpers - there is growing evidence that these interrupt the flow of oxygen and may be a contributory factor
• Lie your baby 'feet to foot' with their feet at the foot of the cot
• Breastfeed your baby as long as possible rather than using formula
• Keep your baby cool - don't allow overheating
• Place their feet at the foot of the cot so they can't wriggle under the covers and don't cover their heads
• Don't fall asleep with your baby in a chair and never sleep your baby in your bed
• Keep your baby's cot in your own room for the first six months
• Follow these guidelines for daytime naps too