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Due Date Calculation Formula:
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Due date calculation estimates the expected delivery date based on the first day of the last menstrual period (LMP) using the standard gestational period of 280 days (40 weeks).
The calculator uses the standard due date formula:
Where:
Explanation: This calculation assumes a regular 28-day menstrual cycle and ovulation occurring on day 14. The 280 days represents 40 weeks of gestation.
Details: Accurate due date estimation is crucial for prenatal care planning, fetal development monitoring, and preparing for delivery. It helps healthcare providers schedule important tests and screenings at appropriate gestational ages.
Tips: Enter the first day of your last menstrual period in the date field. The calculator will provide your estimated due date and current gestational age based on today's date.
Q1: How accurate is the due date calculation?
A: The calculation provides an estimate - only about 5% of babies are born exactly on their due date. Most deliveries occur within 2 weeks before or after the estimated date.
Q2: What if my menstrual cycle is irregular?
A: For irregular cycles, an early ultrasound (first trimester) provides a more accurate due date estimation than LMP-based calculation.
Q3: Why 280 days instead of 9 months?
A: Pregnancy is calculated as 40 weeks from LMP, which equals 280 days. This differs from calendar months due to varying month lengths.
Q4: When should I confirm my due date with a doctor?
A: Always confirm your due date with a healthcare provider during your first prenatal visit, as they may adjust it based on ultrasound measurements.
Q5: Can the due date change during pregnancy?
A: Yes, healthcare providers may adjust the due date based on early ultrasound findings, especially if there's a significant difference from the LMP-based calculation.