Home
Back
NHS Due Date Calculation Formula:
| From: | To: |
The NHS due date calculation from conception date is a standard method used to estimate the expected delivery date. It adds 266 days (38 weeks) to the known conception date, representing the typical gestation period from conception to birth.
The calculator uses the NHS formula:
Where:
Explanation: This calculation assumes a standard 38-week gestation period from conception, which is commonly used in NHS maternity care when the conception date is known.
Details: Accurate due date estimation is crucial for proper prenatal care planning, monitoring fetal development, scheduling important tests, and preparing for delivery. It helps healthcare providers track pregnancy progress and identify any potential complications.
Tips: Enter the known conception date in the date picker. The calculator will automatically compute the estimated due date by adding 266 days. Ensure the conception date is accurate for the most reliable result.
Q1: Why 266 days instead of 280 days?
A: 280 days is calculated from the first day of the last menstrual period (LMP), while 266 days is from the actual conception date. Conception typically occurs about 14 days after LMP.
Q2: How accurate is this calculation?
A: When the conception date is known precisely, this method is very accurate. However, only about 5% of babies are born exactly on their due date.
Q3: What if I don't know my conception date?
A: If the conception date is unknown, NHS typically uses the first day of your last menstrual period (LMP) and adds 280 days, or uses ultrasound dating for more accuracy.
Q4: Can the due date change during pregnancy?
A: Yes, early ultrasound scans may adjust the due date if there's a significant difference between LMP dating and ultrasound measurements.
Q5: What is considered full term?
A: A pregnancy is considered full term between 37 weeks and 41 weeks + 6 days. Babies born during this period have the best outcomes.