1. What is the Due Date Calculator?

The Due Date Calculator estimates when a pregnant woman is likely to give birth based on the date of her last menstrual period (LMP). This calculation uses the standard 280-day (40-week) pregnancy duration.

2. How Does the Calculator Work?

The calculator uses the Naegele's rule:

Where:

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

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

3. Importance of Due Date Calculation

Details: Knowing the estimated due date helps healthcare providers 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 typical cycle length and ovulation pattern.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is this calculator?
A: It's accurate for women with regular 28-day cycles. Only about 5% of women deliver on their exact due date.

Q2: What if my cycles aren't 28 days?
A: For irregular or longer cycles, the due date may need adjustment based on ultrasound measurements in early pregnancy.

Q3: Can the due date change?
A: Yes, early ultrasound measurements may lead to adjustments, especially if they differ significantly from LMP-based calculations.

Q4: What's considered full term?
A: Between 37 weeks (259 days) and 42 weeks (294 days). Babies born before 37 weeks are preterm.

Q5: What if I don't know my LMP?
A: An early pregnancy ultrasound can estimate gestational age, with the most accurate dating occurring between 8-12 weeks.