What should you know about extra growth scans during pregnancy?

A growth scan, also called a fetal growth ultrasound or third trimester scan, can estimate your baby's size and check whether growth is following an expected pattern. The sonographer may measure the baby's head, abdomen and thigh bone, then assess the amount of amniotic fluid, the baby's movements and position, and the placenta. Doppler ultrasound may be used to look at blood flow through the placenta or umbilical cord.

Your clinician may suggest additional monitoring because of a previous pregnancy history, a medical condition, a concern about the baby's growth, changes in fluid, or findings from an earlier appointment. Being offered another scan does not by itself confirm a problem. Ultrasound measurements are estimates, so your team considers the pattern over time alongside your examination and other checks.

Follow the appointment instructions from your maternity service; preparation can vary depending on how far along you are and the type of ultrasound used. Wear clothing that allows access to your abdomen and bring any questions about the reason for monitoring. During the scan, you usually lie back or slightly tilted while gel and a probe are placed over your abdomen. The appointment may take longer than a routine check because several measurements are reviewed.

Ask when and how you will receive the findings, whether another scan is planned, and which changes should prompt a call. Keep attending routine antenatal visits, even if the scan is reassuring, because each appointment checks a different part of your health and your baby's wellbeing.

Contact your maternity unit promptly if your baby's movements are reduced or different from the usual pattern, or if you are worried about movement. Seek urgent maternity advice for vaginal bleeding, leaking fluid, regular painful contractions, severe abdominal pain, severe headache with vision changes, or sudden swelling with feeling unwell. Do not wait for a scheduled growth scan when a new or concerning symptom appears.

You could ask: What prompted the extra scan? Which measurements or blood-flow findings are you checking? When will I hear the result? Will the scan change my appointments or birth plan? What movement pattern should I treat as a reason to call?