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Due Date Calculation Formula:
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The Due Date Calculator estimates the expected delivery date based on the first day of your last menstrual period (LMP). This calculation follows the standard obstetric practice of adding 280 days (40 weeks) to the LMP date.
The calculator uses the standard obstetric formula:
Where:
Explanation: This calculation assumes a regular 28-day menstrual cycle and ovulation occurring on day 14. The actual due date may vary based on individual cycle patterns.
Details: Accurate due date estimation is crucial for proper prenatal care, 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 first day of your last menstrual period in the date field. Ensure the date is accurate for the most reliable due date estimation. The calculator will also show your current gestation in weeks and days.
Q1: How accurate is this due date calculation?
A: This method is accurate for women with regular 28-day cycles. Only about 5% of babies are born exactly on their due date, with most deliveries occurring within two weeks before or after.
Q2: What if my cycles are irregular?
A: For irregular cycles, an early ultrasound dating scan provides more accurate due date estimation than LMP-based calculation.
Q3: Why is pregnancy counted from LMP instead of conception?
A: Medical professionals use LMP because it's a definite date that most women can recall, while conception date is often uncertain.
Q4: Can the due date change during pregnancy?
A: Yes, healthcare providers may adjust the due date based on early ultrasound measurements, especially if there's a significant difference from the LMP-based calculation.
Q5: What is considered full term?
A: Full term is between 37 weeks and 41 weeks 6 days. Babies born before 37 weeks are preterm, while those born after 42 weeks are post-term.