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Pregnancy Due Date Formula:
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The Pregnancy Calculator Using LMP estimates the due date of pregnancy based on the first day of the last menstrual period. This method, known as Naegele's Rule, is widely used in obstetrics to calculate estimated delivery dates.
The calculator uses the standard pregnancy formula:
Where:
Explanation: The calculation assumes a regular 28-day menstrual cycle and adds 280 days (40 weeks) to the first day of the last menstrual period to estimate the due date.
Details: Accurate due date calculation is essential for proper prenatal care, monitoring fetal development, scheduling important tests, and preparing 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 provide your estimated due date and current pregnancy status. Ensure you enter the correct date for accurate results.
Q1: How accurate is the LMP method?
A: The LMP method is generally accurate for women with regular 28-day cycles. For irregular cycles, ultrasound dating may be more precise.
Q2: What if I don't know my LMP?
A: If you're unsure of your LMP, an early pregnancy ultrasound can provide a reliable due date estimate based on fetal measurements.
Q3: Why 280 days instead of 9 months?
A: Pregnancy is calculated as 40 weeks from LMP, which equals 280 days. This accounts for the fact that conception typically occurs about 2 weeks after LMP.
Q4: Can my due date change?
A: Yes, healthcare providers may adjust your due date based on early ultrasound measurements, especially if there's a significant difference from LMP calculation.
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 births occur within two weeks before or after the estimated due date.