1. What is the Due Pregnancy Date Calculation?

The pregnancy due date is typically calculated as 280 days (40 weeks) from the first day of the last menstrual period (LMP). This is known as Naegele's rule and provides an estimate of when a baby is most likely to be born.

2. How Does the Calculator Work?

The calculator uses the standard formula:

Where:

• \( LMP \) — First day of last menstrual period
• \( 280\ days \) — Standard length of pregnancy (40 weeks)

Note: This calculation assumes a regular 28-day menstrual cycle. Adjustments may be needed for women with significantly longer or shorter cycles.

3. Importance of Due Date Calculation

Details: Knowing the estimated due date helps healthcare providers monitor fetal development, schedule important prenatal tests, and determine if the pregnancy is progressing normally.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period in the format YYYY-MM-DD. The calculator will add 280 days to this date to estimate your due date.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is this calculation?
A: Only about 5% of women deliver on their exact due date. Most deliver within 2 weeks before or after the estimated date.

Q2: What if I don't know my LMP?
A: An ultrasound in early pregnancy can provide a more accurate estimate if LMP is unknown or cycles are irregular.

Q3: Does this work for IVF pregnancies?
A: For IVF pregnancies, the calculation is typically based on the embryo transfer date plus 266 days (or 263 days for day 5 embryos).

Q4: Why 280 days if pregnancy is 9 months?
A: Pregnancy is actually about 9.5 months when calculated precisely (40 weeks = 9 months + 1 week).

Q5: Can the due date change?
A: Yes, healthcare providers may adjust the due date based on early ultrasound measurements if they differ significantly from the LMP calculation.