What happens during an obstetric growth scan?

During the scan, the sonographer takes measurements of the baby’s head, abdomen, and thigh bone to estimate growth. They may assess movement, heartbeat, position, the placenta, amniotic fluid, and blood flow through selected vessels. The estimate is interpreted alongside your dates, previous scans, symptoms, and pregnancy history; it is not a direct weighing of the baby.

A scan may be offered when there is concern about growth, fluid, placental function, blood pressure, diabetes, or another pregnancy factor. A result outside the expected pattern does not by itself explain the cause, so your obstetric team may recommend monitoring or additional tests.

Ask whether you need a full bladder or any other preparation; requirements vary by service and stage of pregnancy. Wear comfortable clothing and bring your maternity records if requested. The appointment usually includes time to discuss the findings and the next plan.

If the team suggests repeat scans, attend them even when you feel well. A standard growth scan is different from 3D/4D ultrasound, which creates additional views rather than replacing medical assessment of growth and wellbeing.

Do not wait for a scan if you have vaginal bleeding, leaking fluid, regular painful contractions, severe headache with visual symptoms, sudden swelling, severe abdominal pain, or noticeably reduced fetal movement. Contact your maternity unit urgently for advice about these symptoms.

Ask what prompted the scan, how the measurements compare with earlier findings, whether blood-flow or fluid results need monitoring, and when you will receive the follow-up plan.