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New research on the safety of ultrasound scans in pregnancy

This weekend there are reports in the media of a study on the long term safety of ultrasound in pregnancy. Several years ago, Dr John Newnham, of the King Edward Memorial Hospital in Perth WA, undertook a study to determine the safety for the baby of ultrasound. He used two groups of pregnant women, one group had one ultrasound in their pregnancy, the other 5 scans. When analysing the results, he discovered that quite unexpectedly, the babies who were exposed to more ultrasounds were slightly smaller at birth, by about 30 grams, than the babies who had been exposed to one scan.

At the time, these results attracted much media attention, as they were unexpected and alarming. Many doctors responded by reducing the number of scans ordered in pregnancy and women were advised to limit the exposure of their baby to ultrasound.

Now Newnham has released the results of a study that followed these children for 8 years. His findings now suggest that there are no long term problems for babies exposed to multiple ultrasound scans in pregnancy, news which will reassure many women.

I haven’t yet seen the paper itself and am just reporting here the main gist of the media stories. However, no doubt these reports will encourage the increased use of ultrasound, which certainly has its uses. The research will also have the potential to make practitioners and manufacturers very rich through boosting the number of scans being ordered, and to cost the public health system a lot of money. A review in Australia some years showed that more money was spent on ultrasound scans for pregnant women than on all other prenatal testing procedures put together. This prompted the Federal Government to place a limit of two scans that would be covered by Medicare in our public health system. If women want more, they have to pay for them out of their own pocket, or hope that their private health insurance will cover the costs.

Newnham’s study, published in the Lancet, will make interesting reading. One caution he did make was that the ultrasound machines in use today are far more powerful that those available when he did his research, so we still don’t know what levels of actual exposure are safe for the unborn baby. It is the level of exposure that is the critical factor, and given that babies also receive ultrasound from hand held dopplers (used to listen to the baby’s heartbeat) and from electronic fetal monitoring (CTGs) during labour, the total dose a baby received could be quite high.

Until these factors can be quantified, it seems to me that the only safe way to proceed is to limit the number of ultrasound scans in pregnancy (and the use of sonicaids and CTGs) to the absolute minimum, especially with the higher powered equipment that is now in use. If any of this equipment is found, perhaps many years later, to have cause untoward effects for the baby, then many parents will be looking for compensation. Better to be safe than sorry, I believe, especially as there are perfectly good alternatives available, such as Pinard stethoscopes, that can be used when no specific problems need closer scrutiny.

Posted by andrea at December 05, 2004 06:56 AM