EDD From Ultrasound Guide
Why Ultrasound Dating Helps
Ultrasound dating gives a practical estimate when a last period date is uncertain. It uses the gestational age printed on a scan report. The calculator converts that age into total pregnancy days. Then it works backward from the scan date. This gives an estimated last menstrual period. It also adds the remaining pregnancy days to estimate the due date.
When Scan Timing Matters
This method is useful during early pregnancy. First trimester measurements often give the strongest dating value. Later scans can still help. Yet fetal size varies more as pregnancy grows. A clinician should decide whether a due date should replace an older date. The tool supports that discussion by showing clear differences and timing windows.
What The Result Shows
The result includes more than one date. It shows the calculated EDD, estimated conception date, and current gestational age. It also marks trimester status and days remaining. A delivery window from thirty seven to forty two weeks is included. This window helps users understand that an EDD is not a guaranteed birth date.
Comparing With LMP
The optional LMP comparison is helpful. Enter a known last period date to compare methods. The calculator checks the gap between ultrasound dating and period dating. It then displays a review note based on the scan age. Large gaps should be discussed with a qualified maternity professional.
Best Input Practice
For best results, copy values directly from the ultrasound report. Enter weeks and days exactly as shown. Use the exam date, not the appointment booking date. Select the reference date when checking gestational age for today or another visit. Avoid guessing if the report is unclear.
Important Safety Note
This page is a planning aid. It is not a diagnosis. It cannot evaluate fetal growth, viability, or risk. It also cannot replace a prenatal record. Use it for organizing dates, preparing questions, and creating a report for appointments. Always follow advice from your doctor, midwife, or obstetric team.
Downloadable Records
Reports can be downloaded for simple records. The CSV file helps with spreadsheets. The PDF button creates a printable summary. These options make it easier to keep scan based dating, milestones, and comparison notes together.
Record Keeping
Keep the saved report with the scan image. Bring both to prenatal visits. Clear records reduce confusion when several dates appear in different notes during later care.