1. What is the NHS Pregnancy Dates Calculator?

The NHS Pregnancy Dates Calculator estimates your due date based on your last menstrual period (LMP) using the standard NHS calculation method. This provides an accurate timeline for pregnancy monitoring and prenatal care planning.

2. How Does the Calculator Work?

The calculator uses the NHS standard formula:

Where:

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

Explanation: This calculation assumes a regular 28-day menstrual cycle and ovulation occurring on day 14. The result provides the estimated date of delivery.

3. Importance of Pregnancy Dating

Details: Accurate pregnancy dating is essential for proper prenatal care, scheduling important tests and scans, monitoring fetal development, and planning 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 calculations.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is the LMP method?
A: The LMP method is generally accurate for women with regular 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 accurate dating measurements.

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: Can my due date change?
A: Yes, your due date may be adjusted after your first ultrasound scan if there's a significant difference from the LMP calculation.

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.