1. What is the Due Date Calculation?

The expected due date is calculated as 280 days (40 weeks) from the first day of the last menstrual period (LMP). This is known as Naegele's rule and is the standard method for estimating delivery dates.

2. How Does the Calculator Work?

The calculator uses the simple formula:

Where:

• \( LMP \) — First day of last menstrual period
• \( 280\ days \) — Equivalent to 40 weeks gestation

Explanation: This calculation assumes a regular 28-day menstrual cycle with ovulation occurring on day 14.

3. Importance of Due Date Calculation

Details: Accurate due date estimation is crucial for prenatal care scheduling, monitoring fetal development, and determining if 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.

Q2: What if my cycle isn't 28 days?
A: For irregular or longer cycles, the due date may need adjustment. Consult your healthcare provider.

Q3: When should I get an ultrasound to confirm?
A: Early ultrasound (8-12 weeks) provides the most accurate dating. Later ultrasounds are less reliable for dating.

Q4: Why 280 days if pregnancy is 9 months?
A: Months vary in length. 280 days equals 40 weeks, which is the standard medical definition of full term.

Q5: What if I don't know my LMP?
A: An early ultrasound can estimate gestational age if LMP is unknown or cycles were irregular.