1. What is NZ Pregnancy Date Calculator?

The NZ Pregnancy Date Calculator estimates the due date based on the last menstrual period (LMP) using the standard calculation of LMP + 280 days. This is the most common method used in New Zealand healthcare for estimating delivery dates.

2. How Does the Calculator Work?

The calculator uses the standard pregnancy calculation:

Where:

• \( LMP \) — Last Menstrual Period (start date)
• \( 280 days \) — Standard pregnancy duration (40 weeks)

Explanation: This calculation assumes a regular 28-day menstrual cycle and ovulation occurring on day 14. The 280 days represents 40 weeks of gestation.

3. Importance of Due Date Calculation

Details: Accurate due date estimation is crucial for prenatal care planning, monitoring fetal development, scheduling important tests, and preparing for delivery.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period. Ensure the date is accurate as this forms the basis for all subsequent pregnancy dating.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is the LMP + 280 days method?
A: This method is accurate for women with regular 28-day cycles. Only about 5% of women deliver exactly on their estimated due date.

Q2: What if my cycle is longer or shorter than 28 days?
A: For irregular cycles, an early ultrasound dating scan provides more accurate due date estimation.

Q3: Why 280 days specifically?
A: 280 days represents 40 weeks of pregnancy, calculated from the first day of the last menstrual period rather than conception date.

Q4: When should I confirm my due date with healthcare provider?
A: Always confirm your due date with your midwife or doctor, especially if you have irregular periods or uncertain LMP date.

Q5: Can the due date change during pregnancy?
A: Yes, due dates may be adjusted based on ultrasound measurements, particularly if there's significant discrepancy with LMP dating.