1. What is the Perinatology Due Date Calculation?

The perinatology method calculates estimated due date (EDD) by adding 280 days (40 weeks) to the first day of the last menstrual period (LMP). This is the standard method used in obstetrics for estimating delivery dates.

2. How Does the Calculator Work?

The calculator uses the standard perinatology equation:

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. The calculator also displays current gestational age based on today's date.

3. Importance of Due Date Calculation

Details: Accurate due date estimation is crucial for proper prenatal care, timing of tests, monitoring fetal growth, and managing high-risk pregnancies.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period. The calculator will show your estimated due date and current gestational age.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is this due date calculation?
A: For women with regular 28-day cycles, it's accurate within ±5 days. Only about 5% of women deliver on their exact due date.

Q2: What if my cycles aren't 28 days?
A: For irregular cycles, ultrasound dating in the first trimester is more accurate than LMP-based calculation.

Q3: Why 280 days/40 weeks?
A: This is the standard gestation period used in obstetrics, counting from LMP (which is typically 2 weeks before conception).

Q4: When is the best time to confirm with ultrasound?
A: First trimester ultrasound (especially 8-12 weeks) provides the most accurate dating.

Q5: What is considered full term?
A: 37-42 weeks is considered term. Before 37 is preterm, after 42 is post-term.