Q&A: Antibiotics and cerebral palsy

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By Michelle Roberts Health reporter, BBC News

Cerebral palsy affects one in 400 birthsA study has linked a small number of cases of cerebral palsy to antibiotics given to women in premature labour.

What was the study?

The children involved were born to women taking part in a trial called Oracle set up to investigate if giving antibiotics - which might tackle an underlying symptomless infection - during premature labour would improve outcomes for babies.

What did the researchers find?

The Oracle study involving 4,148 women found the antibiotic erythromycin had immediate benefits for women in premature labour (before 37 weeks gestation) whose waters had broken. It delayed onset of labour and reduced the risk of infections and breathing problems in babies.

This is important because prematurity, which affects one in eight babies in the UK, is the leading cause of disability and of infant death in the first month after birth.

However, in the longer-term, erythromycin and another antibiotic called co-amoxiclav appeared to have harmful effects for some of the children - namely those born to mothers in premature labour whose waters had not broken.

When they were re-assessed at the age of seven, three times as many of these children had cerebral palsy as the children whose mothers did not receive antibiotics in the same circumstances - 35 versus 12, respectively.

What is cerebral palsy?

Cerebral palsy is not a disease or an illness. It is a physical impairment disorder of varying severity that affects movement and is most commonly the result of failure of part of the brain to develop, either before birth or in early childhood.

This is sometimes because of complications in labour, extreme prematurity or illness just after birth. Infections during pregnancy or infancy can also cause cerebral palsy.

Does this mean antibiotics cause cerebral palsy?

Experts say no it does not.

There is a link between antibiotic use and cerebral palsy, but this does not necessarily mean one is caused by the other, particularly as there was no increased risk of cerebral palsy in the babies born to women whose waters had broken.

The researchers say: "We will never know what specifically caused the cerebral palsy in any individual child whose mother took part in the trial, only that there is a small increased risk for women who had both antibiotics."

What could explain the results?

The Medical Research Council-funded researchers believe cerebral palsy is unlikely to be a direct effect of the antibiotic but rather due to factors involved in prolonging a pregnancy that might otherwise have delivered early.

When silent infection is provoking premature labour, treatment with low doses of antibiotics might only suppress rather than eradicate infection from inside the womb, prolonging pregnancy and allowing the unborn baby continued exposure to a "hostile" environment, they say in The Lancet journal.

What advice is being given in light of the findings?

The Royal College of Obstetricians and Gynaecologists say the findings do not mean that antibiotics are unsafe for use in pregnancy. Pregnant women showing signs of infection should be treated promptly with antibiotics.

Antibiotics save lives and pregnant women with possible or obvious infections must be considered for treatment with antibiotics, says the Chief Medical Officer in a letter to doctors and midwives advising them of the study findings.

Current guidance says women in premature labour whose waters have not broken should not routinely be given antibiotics and this advice stands.

Leaflets will be sent to any women who took part in the study and request it. A helpline is also available for study participants on 0800 085 2411 between 0930 and 1630 BST.

NHS Direct has information available for other members of the public.

What now?

The results were unexpected and the Medical Research Council is considering what further research could shed more light on the findings. The MRC will be convening an expert group to look at what potential research avenues could be explored to understand what mechanisms may be involved.

Where can I find the scientific papers?

They are available from:<a class="bodl" href="http://www.le.ac.uk/oraclechildren">ORACLE Children Study website</a>