Accurate figures are aid to medical decisions

Press, 28 May 1984, Page 14

Accurate figures are aid to medical decisions

By

JACQUELINE STEINCAMP

Extremely detailed Bristish statistics on congenital abnormalities are compiled in a central national register. The data is assisting decision-making by parents' and doctors where fetal abnormalities are probable or proven, according to a British cancer researcher, Dr Jocelyn Chambers. The British register for congenital abnormalities was set up as a result of the thalidomide disaster. It is designed to pinpoint increases of any specific type of abnormalities, and any unusual regional rates.

Dr Chambers said that in the last 15 years, congenital abnormality rates have stayed fairly constant in Britain. There has been a slight rise in malformations of the external genitals, and a big fall in malformations of the central nervous system, with a corresponding rise in terminations of pregnancy for abnormalities such as spina bifida. “Nevertheless, central nervous system abnormalities are declining markedly, possibly due to the improved nutrition of mothers,” she said. Dr Chambers is attached to the Royal Marsden Hospital in Surrey, one of four experimental cancer hospitals established in Britain in the early seventies; During her visit to New Zealand to address the Women's Health Conference in Dunedin, she spoke this week to members of the Christchurch branch of the Australia and New Zealand society for Epidemiology and Research into Community Health. Dr Chambers pointed out that it was impossible to test during pregnancy or infancy for abnormalities and genetic defects which developed in later life. These include Huntington’s chorea, which strikes around the age of 40. Dr Chambers outlined the range of responses to congenital abnormalities. These range from primary prevention, such as rubella immunisation and genetic counselling; effective treatments of the

newborn, such as surgical correction and medical treatments for phenylketonuria and hypothyroidism. Terminations are recommended 'lot neural tube defects, Down’s Syndrome, and thalassaemia, a disease affecting Greek Cypriots in particular. “Screening and treatment for phenylketonuria is particularly cost-effective. “Of the 600,000 United Kingdom births a year, only a very few babies are missed — about five in the years 1974-78. “Each case that is treated saves the country about £ 85,000 overall.” Immunisation of schoolgirls has caused a marked decrease in the incidence of defects caused by rubella. “There are still epidemics of rubella, however, and between 200 and 250 chil-

dren are damaged every year. “Pregnancies terminated because of suspected rubella jumped from an average of 200 per annum to 800 to 900 in the epidemic years of 1978 and 1979. “Because schools have to obtain the permission of parents before immunisation can be carried out, only about 70 per cent of British schoolgirls are immunised,” she said. Dr Chambers described the risks and the benefits of screening for abnormalities. This is usually done by testing the mother’s blood, and by ultrasound and amniocentisis (an analysis of the components of the amniotic fluid in which the baby floats). “Though we are able to prevent about 150 neural tube defects being born out of every 100,000 pregnancies, about 30 babies will be

harmed in some way by the procedure,” Dr Chambers said. “This is one reason why it is important that it should be the parents themselves who decide whether or not to undertake amniocentisis — not the health service, the doctor, or the obstetrician.” Amniocentisis is used so extensively on mothers in the 45-plus age-group that the greatest numbers of Down’s Syndrome babies being born are to mothers in the 20-to-24 age group,, because it is they who have the largest number of babies, Dr Chambers said.