Whilst in high-income countries most babies grow well in the womb, sometimes the mother might have a medical problem, such as diabetes, high blood pressure, heart or kidney problems, that impacts on the growth of the baby. Also, sometimes babies just do not grow well for reasons we do not fully understand. These babies with poor growth can be at increased risk of complications which can result in increased mortality or morbidity. Doppler ultrasound detects changes in the pattern of blood flow through the baby's circulation. It may be that problems for the baby could be identified through these changes. Interventions, like early delivery, might then be able to reduce the mortality and morbidity. However, it may also be that the use of Doppler ultrasound could increase the use of caesarean section.
The review of trials identified 18 studies involving just over 10,000 women. These studies compared the use of Doppler ultrasound of the babies vessels in utero with no Doppler or with cardiotocography (CTG sometimes known as electronic fetal monitoring). There was a reduction in the number of babies who died, fewer caesarean sections and operative deliveries, but the quality of the studies was not high and there remains some uncertainty here. Further studies of high quality would, therefore, be helpful.