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Due Date Formula:
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Due date calculation estimates the expected delivery date based on the first day of the last menstrual period (LMP). This method uses Naegele's rule, adding 9 months and 7 days to the LMP date.
The calculator uses the standard obstetric formula:
Where:
Explanation: This calculation assumes a 28-day menstrual cycle with ovulation occurring on day 14. The pregnancy duration is approximately 40 weeks from the LMP.
Details: Accurate due date estimation is crucial for prenatal care planning, monitoring fetal development, scheduling 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 duration in weeks and days.
Q1: How accurate is this due date calculation?
A: This method provides a good estimate, but only about 5% of babies are born exactly on their due date. Most births occur within two weeks before or after the estimated date.
Q2: What if my menstrual cycle is longer or shorter than 28 days?
A: For cycles longer than 28 days, add the extra days to the due date. For shorter cycles, subtract the difference. An ultrasound can provide a more accurate estimate.
Q3: When is the due date typically confirmed?
A: Healthcare providers usually confirm the due date during the first trimester ultrasound, which is more accurate than LMP-based calculation.
Q4: Can the due date change during pregnancy?
A: Yes, based on ultrasound measurements and fetal growth patterns, healthcare providers may adjust the due date, especially if early ultrasounds show significant variation from LMP-based calculation.
Q5: What is considered full term pregnancy?
A: A pregnancy is considered full term between 39 weeks 0 days and 40 weeks 6 days. Early term is 37-38 weeks, and late term is 41-41 weeks 6 days.