Is there a link between snoring and stillbirth?

Do some pregnant women stop breathing in their sleep without even realising it? Doctors fear this interrupted breathing could slow unborn babies' growth, putting them at risk of death and cerebral palsy. If so, a ready-made treatment for mothers offers new hope to keep their babies healthy.

What's the problem and who does it affect?

Growth restriction causes stillbirth and cerebral palsy

Around one in twenty unborn babies grows abnormally slowly in its mother's womb. [1] Sadly, this growth restriction is a leading cause of stillbirth and cerebral palsy. It also increases the chance of getting heart disease and diabetes in later life.

Anxious parents are normally powerless to help. Some babies have to be delivered early, but premature birth carries its own potentially devastating consequences.

Are pregnant women susceptible to a breathing disorder?

Doctors think it's possible that some babies don't grow properly because their pregnant mothers have a breathing disorder, called sleep apnoea, without even realising it. The typical symptoms of snoring and daytime sleepiness often go unnoticed.

People with sleep apnoea actually stop breathing, for up to a minute at a time, sometimes hundreds of times a night. Doctors fear this could stop babies from growing properly in the womb, possibly because of low oxygen levels in the mothers' blood.

What is the project trying to achieve?

Researchers working on this project aim to answer two key questions.

How many pregnant women have sleep apnoea?

Researchers will study 120 heavily pregnant women selected at random. The women will wear small devices, called pulse oximeters, on their wrist and hand as they sleep each night at home. The oximeter will monitor oxygen levels in the women's blood so researchers can identify which women have sleep apnoea.

Can sleep apnoea slow the growth of unborn babies?

In the second part of the study, researchers aim to compare 100 women with normal pregnancies and 100 women whose babies have growth restriction, looking for any difference in the proportion of women with sleep apnoea. This should identify any link between sleep apnoea and small babies.

Professor Thornton is a leading expert in growth restriction and clinical trials. He published the first case report of apparently successful treatment of sleep apnoea in pregnancy. His group are collaborating with Professor John Britton a leading researcher in sleep apnoea outside pregnancy.

Professor Thornton is also the principle investigator of a study known as GRIT - the Growth Restriction Intervention Trial. This randomised trial is investigating how the timing of birth affects the subsequent health of babies with growth restriction. The trial suggests that an early delivery may be harmful.

Who stands to benefit from this research and how?

Could treating mothers help their unborn babies?

If pregnant women are susceptible to sleep apnoea, and the disorder does cause unborn babies to grow too slowly, then there's a ready-made treatment for the mothers that may also help their babies.

It's normally easy to treat sleep apnoea - sufferers simply wear a mask that gently blows air into their nose as they sleep. With this effective cure, pregnant mothers could expect to breathe normally at night and oxygen levels in their blood should return to normal.

Unborn babies have even more to gain from their mother's treatment. Clinical trials would reveal whether treating mothers helps their unborn babies to grow properly during pregnancy, and whether it can cut the rate of stillbirth and cerebral palsy.

Anecdotal evidence from previously reported case histories is promising. One woman with severe sleep apnoea, for example, lost a baby during pregnancy, but went on to have a healthy baby with the help of treatment.

References

1. Peleg D, Kennedy CM, Hunter SK. Intrauterine growth restriction: identification and management. Am Fam Physician 1998 Aug;58(2):453-60,466-7
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