1. What is the Due Date Prediction?

The due date prediction estimates when a pregnant woman is likely to give birth based on her last menstrual period (LMP). This calculation uses Naegele's rule which adds 280 days (40 weeks) to the first day of the LMP.

2. How Does the Calculator Work?

The calculator uses the standard obstetric formula:

Where:

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

Explanation: This calculation assumes a regular 28-day menstrual cycle with ovulation occurring on day 14. Actual delivery dates may vary by ±2 weeks.

3. Importance of Due Date Calculation

Details: An accurate due date helps monitor fetal development, schedule prenatal tests, and identify potential preterm or post-term pregnancies.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period. For best accuracy, you should know your cycle length and ovulation 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 cycles, ultrasound dating in early pregnancy is more accurate than LMP-based calculation.

Q3: When should I see a doctor?
A: Schedule prenatal care as soon as you know you're pregnant, regardless of the calculated due date.

Q4: Can the due date change?
A: Yes, early ultrasound may adjust the due date based on fetal measurements.

Q5: What's the difference between gestational age and fetal age?
A: Gestational age counts from LMP (about 2 weeks longer than actual fetal age which counts from conception).