1. What is HSE EDD Calculator?

The HSE EDD (Estimated Due Date) Calculator calculates the expected delivery date based on the last menstrual period using the standard formula of LMP + 280 days, as recommended by the Health Service Executive.

2. How Does the Calculator Work?

The calculator uses the standard obstetric formula:

Where:

• \( EDD \) — Estimated Due Date
• \( LMP \) — First day of Last Menstrual Period
• \( 280 \text{ days} \) — Standard pregnancy duration (40 weeks)

Explanation: This calculation method, known as Naegele's Rule, assumes a 28-day menstrual cycle and ovulation occurring on day 14.

3. Importance of Due Date Calculation

Details: Accurate due date estimation is crucial for prenatal care scheduling, fetal development monitoring, and preparing for delivery. It helps healthcare providers track pregnancy progress and identify potential complications.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period in the date field. The calculator will determine your estimated due date and current weeks of pregnancy based on today's date.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is the LMP method?
A: The LMP method is generally accurate for women with regular 28-day cycles. For irregular cycles, ultrasound dating in early pregnancy may be more precise.

Q2: What if I don't know my LMP?
A: If you're unsure of your LMP, an early pregnancy ultrasound (before 14 weeks) can provide an accurate due date estimation.

Q3: Why 280 days instead of 9 months?
A: Pregnancy is calculated as 40 weeks from LMP, which equals 280 days. This accounts for the fact that conception typically occurs about 2 weeks after LMP.

Q4: Can my due date change?
A: Yes, healthcare providers may adjust your due date based on early ultrasound measurements or if your menstrual cycles are irregular.

Q5: What percentage of babies are born on their due date?
A: Only about 5% of babies are born exactly on their due date. Most births occur within two weeks before or after the estimated date.