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Naegele's Rule Formula:
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Naegele's Rule is a standard way of calculating the estimated due date (EDD) for a pregnancy. It is based on the assumption of a 28-day menstrual cycle with ovulation occurring on day 14. The rule adds 280 days (40 weeks) to the first day of the last menstrual period (LMP).
The calculator uses Naegele's Rule formula:
Where:
Explanation: This calculation estimates the delivery date by adding 280 days (40 weeks) to the first day of your last menstrual period.
Details: Accurate due date estimation is crucial for prenatal care scheduling, monitoring fetal development, and planning for delivery. It helps healthcare providers track pregnancy progress and identify potential complications.
Tips: Enter the first day of your last menstrual period in the date field. The calculator will automatically compute your estimated due date based on Naegele's Rule.
Q1: How accurate is Naegele's Rule?
A: Naegele's Rule provides a good estimate, but only about 5% of women deliver on their exact due date. Most deliveries occur within two weeks before or after the estimated date.
Q2: What if my menstrual cycle isn't 28 days?
A: Naegele's Rule assumes a 28-day cycle. If your cycle is significantly longer or shorter, your healthcare provider may adjust the due date accordingly.
Q3: Can ultrasound change the due date?
A: Yes, early pregnancy ultrasounds (before 14 weeks) can provide a more accurate due date measurement based on fetal size and development.
Q4: Why 280 days?
A: 280 days represents 40 weeks of pregnancy, which is the typical gestation period calculated from the first day of the last menstrual period.
Q5: Does this work for IVF pregnancies?
A: For IVF pregnancies, the conception date is known precisely, so due dates are typically calculated based on the embryo transfer date plus 266 days (38 weeks).