Sudden infant death syndrome, SIDS, cot death or crib death is the sudden and unexpected death of a baby less than two years of age who is seemingly healthy – death usually occurs during sleep. The majority of SIDS occur during the first six months of the baby’s life.
According to the NHS (National Health Service), UK, approximated 300 babies die from SIDS in the United Kingdom annually. In the USA there are approximately 2,500 cases of SIDS each year, according to the American SIDS Institute. It is the most common reason for death for babies aged one month or more. Babies born with a low birth bodyweight, as well as premature babies have a higher risk of SIDS, compared to other babies. Cot deaths are more common among baby boys than baby girls.
For parents an SIDS event is devastating and shocking – it occurs without warning and there is rarely any definitive cause.
Even though SIDS is the most common cause of infant deaths, the risk is extremely small.
Scientists have found some factors linked to SIDS, as well as identifying steps parents can take to minimize the risk, such as placing to sleep the baby on his/her back.
A risk factor is something which increases the likelihood of developing a condition or disease. For example, obesity significantly raises the risk of developing diabetes type 2. Therefore, obesity is a risk factor for diabetes type 2.
SIDS can affect any baby. However, researchers have linked the following risk factors that may raise a baby’s risk:
- Gender – male babies are more susceptible to SIDS than female babies.
- Age – babies (infants) aged between 1 and 6 months are more susceptible, especially during the second and third months of life.
- Low birth bodyweight
- Being born prematurely
- Ethnic origin – babies of African, Indian or Native Alaskan ancestry have a higher risk of SIDS, compared to other babies (source: The Mayo Clinic, USA).
- Placing the baby to sleep – if a baby sleeps on his/her stomach the risk of SIDS is much greater. Those at highest risk are babies who have been placed on their backs regularly, and one day are placed on their stomachs.
- Smoking mothers – the percentage of SIDS babies whose mothers smoke during or after pregnancy is much higher than in the rest of the population.
- Mothers who use drugs – if a mother uses cocaine, heroin or methadone during her pregnancy, her baby has a significantly higher risk of SIDS.
- Passive smoking – babies exposed to environmental tobacco smoke are more likely to develop SIDS compared to babies in a smoke-free environment.
- Birth date – a higher percentage of babies born in the autumn (fall) or winter experience SIDS, compared to babies born in the spring or summer.
- Temperature – if the baby is overwrapped and overdressed and subsequently gets too hot, he/she has a higher risk, especially if he/she is placed down on his/her stomach.
- Recent respiratory infection – for a period of four weeks after a respiratory infection a baby has a higher risk of SIDS.
- Family history – any baby whose sibling died of SIDS has a higher risk.
- Placental abnormalities – babies whose mothers had placenta previa have a higher risk.
- Slow weight gain during pregnancy – mothers who had slow weight gain during pregnancy are more likely to have SIDS babies.
- Anemia – a baby whose mother had anemia during her pregnancy has a higher risk of SIDS.
- Sexually transmitted diseases – mothers with a history of STDs (sexually transmitted diseases) run a higher risk of having babies with SIDS.
SIDS incidence is gradually falling as people respond to educational campaigns regarding placing babies on their backs – even so, it is still the leading cause of infant death.
Scientists say SIDS is not primarily caused by suffocation, vomiting, choking, infection or birth defects.
Nobody is really sure what occurs to make SIDS happen. They believe several factors converge, such as perhaps some possible brain or heart defect, sleeping on their stomach, going through a key developmental period, and possibly some environmental stressors. The following three factors are known as The Triple Risk Model:
- Critical developmental period
- An outside stressor
The following may or may not be involved in SIDS, experts suggest:
- Nervous system characteristics – a higher-than-normal proportion of babies who die of SIDS have brainstems that have not matured as fully as those of other babies of the same age. It is also possible that myelin has not developed well in babies who die of SIDS – myelin is a fatty substance involved in nerve signal transmission.
- Hypoxia (low oxygen) – experts believe that some babies respond differently to lower levels of oxygen.
- Long QT syndrome – this is an inherited defect in heart rhythm – the heart beats extremely rapidly – that predisposes to syncope (part or total loss of consciousness with interruption of awareness of oneself and ones surroundings) without warning. There is ongoing research aimed at finding a link between SIDS and long QT syndrome. One study found that 10% of SIDS babies had a gene defect linked to long QT syndrome.
- Vaccines – a study carried out by the American Academy of Pediatrics found no link between childhood immunizations and SIDS.
Researchers from the Geisel School of Medicine at Dartmouth, NH, recently investigated the role of serotonin on breathing responses in sleeping infants. The findings, published in Experimental Physiology, offer a new avenue of research into sudden infant death syndrome.
SIDS is not common; in fact it is quite rare. Parents with newborns should be aware of the possible risks, but at the same time not be overly anxious and worried about it. The following steps may help lower the risk:
- Sleeping position – place your baby down to sleep on their back; their feet should touch the foot of the cot (crib, baby bed). Bedding, such as sheets and blankets should be tucked in and should not be higher than the baby’s shoulders. Tucking bedding in helps prevent smothering of the baby’s head.
- Waking position – a variety of positions is ideal when the baby is awake. Let them lie on their stomach and play; but make sure they do not fall asleep in that position. Lying on their tummies while awake helps them control their head and encourages development.
- Smoking – studies indicate that exposing a baby to tobacco smoke can significantly raise SIDS risk. Parents who find it difficult to give up should seriously consider smoking outside. Just smoking with an open window does not eliminate the second-hand smoke SIDS link.
- Sharing your bed with your baby – doctors in the UK, USA, Canada, Australasia and many other countries say that a baby should ideally sleep in their own crib or cot during their first six months of life – preferably in the same room.
- Using a dummy (soother, pacifier) – some studies have found that babies who use a dummy while sleeping have a lower risk of SIDS. This may be because the dummy helps air get into the airways, even if the baby’s head is covered with bedding. Breastfed babies should not have a dummy until after one month of age.
- Temperature – the room should be at a comfortable temperature. A hot room may increase the risk of SIDS. A baby may overheat because the room is too warm, or there are too many clothes and blankets, etc. In the UK doctors say the ideal room temperature is between 16C and 20C (61F – 68F). Do not use hot water bottles or electric blankets. Do not place the cot or crib next to a heat source, such as a radiator.
- Bedding – use a firm mattress. Avoid fluffy bedding, or bedding full of padding. While the baby is asleep do not leave fluffy toys and pillows nearby. Use a sleep sack which eliminates the need for additional covers.