1. What is the Due Date Calculation?

The due date calculation based on ovulation date adds 266 days (38 weeks) to the known ovulation date. This method is more accurate than last menstrual period (LMP) dating for women who track their ovulation.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• Ovulation Date — The known date of ovulation
• 266 days — The average length of pregnancy from ovulation

Explanation: Human pregnancy typically lasts 266 days (38 weeks) from conception (ovulation) to delivery. This is more precise than the common 280-day estimate which is based on the first day of the last menstrual period.

3. Importance of Accurate Due Date

Details: An accurate due date helps in proper prenatal care scheduling, monitoring fetal growth, and determining if a pregnancy is post-term. It's especially important for women with irregular cycles who can't rely on LMP-based calculations.

4. Using the Calculator

Tips: Enter the exact date of ovulation (if known from tracking methods like basal body temperature, ovulation predictor kits, or ultrasound). The calculator will show your estimated due date and current pregnancy progress.

5. Frequently Asked Questions (FAQ)

Q1: Why 266 days instead of 280?
A: 280 days (40 weeks) is counted from the first day of the last menstrual period (LMP), while 266 days counts from ovulation/conception (typically 14 days after LMP in a 28-day cycle).

Q2: How accurate is this method?
A: This is the most accurate method if you know your exact ovulation date, with only 4% of women delivering on their due date but most within a week of it.

Q3: What if I don't know my ovulation date?
A: If you don't know your ovulation date, use a LMP-based calculator or consult your healthcare provider for an ultrasound dating.

Q4: Does this account for leap years?
A: Yes, the calculator automatically accounts for leap years in the date calculation.

Q5: Can the due date change?
A: Early ultrasound measurements may adjust the due date, especially if there's more than 5-7 days difference from the ovulation-based calculation.