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NHS EDD Pregnancy Calculation:
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The NHS EDD (Estimated Due Date) Pregnancy Calculator estimates the expected delivery date based on the last menstrual period using the standard NHS calculation method of LMP + 280 days.
The calculator uses the NHS standard formula:
Where:
Explanation: This calculation follows the Naegele's rule, which is the standard method used by the NHS for estimating due dates based on menstrual history.
Details: Accurate EDD calculation is crucial for proper prenatal care scheduling, fetal development monitoring, and planning for delivery. It helps healthcare providers track pregnancy milestones and identify any potential issues.
Tips: Enter the first day of your last menstrual period (LMP) in the date field. Ensure the date is accurate as this forms the basis for all subsequent pregnancy dating.
Q1: How accurate is the LMP-based EDD calculation?
A: For women with regular 28-day cycles, it's quite accurate. However, early pregnancy ultrasound dating may be more precise, especially if cycles are irregular.
Q2: What if my menstrual cycles are irregular?
A: If cycles are longer than 28 days, the EDD may need adjustment. An early dating scan (usually at 8-14 weeks) provides the most accurate due date.
Q3: Why 280 days specifically?
A: 280 days represents 40 weeks of pregnancy, calculated from the first day of the last menstrual period rather than conception date.
Q4: Can the due date change during pregnancy?
A: Yes, NHS guidelines allow for EDD adjustment based on early ultrasound measurements, which are considered more accurate than LMP dating alone.
Q5: What percentage of babies are born on their due date?
A: Only about 5% of babies are born exactly on their due date. Most are born within two weeks before or after the estimated date.