A SOFTWARE trick used to pick out enemy targets on military radar could help doctors spot problems during labour. The non-invasive system can record a baby鈥檚 electrocardiogram (ECG) trace during delivery and can also reveal the strength of the mother鈥檚 contractions.
Doctors can already monitor a baby鈥檚 heart rate during labour using a technique called cardiotocography (CTG). But its output is difficult to interpret, and gives only the average of the heart rate over three beats.
An ECG trace, a recording of the electrical signal from the heart itself, is more accurate and can reveal if a baby is not receiving enough oxygen, for example, or is suffering a heart arrhythmia. But at the moment the only way to get an ECG trace during delivery is to insert a sensor under the skin in the baby鈥檚 head, which can only be done after the cervix dilates and is stressful for mother and baby.
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The non-invasive system records signals from 12 electrodes on the mother鈥檚 abdomen, separating out useful components from background noise from muscles other than the heart, or interference from electrical equipment. It鈥檚 rather like picking out different voices at a cocktail party, says Mark Smith of Qinetiq, the British defence research company in Malvern that developed the system.
The team has already shown that it can distinguish between traces from the mother鈥檚 and the baby鈥檚 heart during pregnancy, even picking apart the signals from triplets (British Journal of Obstetrics and Gynaecology, vol 110, p 668). Now they have extended the study to mothers in labour. In initial tests on 16 women, they were able to record the fetal ECG in 12 cases.
The system should allow doctors to spot any problems early on, says team member Myles Taylor at the Royal Devon and Exeter Hospital in the UK, and help doctors to rule out unnecessary Caesarean deliveries in borderline cases.
The researchers also found they could measure the mother鈥檚 contractions directly, using the electrical signals from the muscles. At present, the sole available method is to place a strain gauge across the abdomen, which gives only a crude measurement.
