Midwife Nikki Khan replies: This is a form of ultrasound that monitors the blood flow from the placenta to your baby. It helps doctors to check that the baby is getting enough nutrients and that your placenta is working effectively. It's not an invasive test and won't harm your baby.

Doppler scanning uses black and white or colour images to identify the different blood vessels in the umbilical cord so that the blood flow can be traced. One colour goes from the placenta to the baby and another from the baby to the placenta. It can be given during the anomaly scan, and safely repeated.