What should you know about scan dates pregnancy?

The scan can help locate the pregnancy, check whether it is developing in the uterus, and assess cardiac activity when visible at the stage being examined. Measurements of the pregnancy are used to estimate gestational age. This estimate may differ from a calculation based only on the first day of the last menstrual period, especially when cycles are irregular or ovulation occurred later than expected.

The result is an estimate, not a promise that labour will begin on a particular day. The sonographer or clinician will explain what was visible, whether another scan is needed, and which date should be used for ongoing pregnancy care.

Bring the date of your last menstrual period if you know it, along with details of previous scans and any fertility treatment dates. Follow the clinic’s instructions about eating, drinking, and bladder preparation because these can vary with the scan method and stage of pregnancy. Ask when you will receive the written report and how the estimated date will be recorded.

A later screening appointment may include a nuchal translucency scan. Keep each report so dates and findings can be compared across your care.

Contact your maternity or clinical team promptly if you have heavy bleeding, severe or one-sided abdominal pain, fainting, shoulder-tip pain, or feel acutely unwell. These symptoms need assessment regardless of the date shown on a scan.

What gestational age does the measurement suggest? Which due date should guide my care? Was the pregnancy seen in the uterus, and was cardiac activity visible? Do I need a repeat scan or a nuchal translucency scan?