1. What Is NHS Pregnancy Calculation?

The NHS pregnancy calculation estimates the due date based on the first day of the last menstrual period (LMP). This method adds 280 days (40 weeks) to the LMP date to determine the estimated due date (EDD).

2. How Does The Calculator Work?

The calculator uses the standard NHS pregnancy calculation formula:

Where:

• \( EDD \) — Estimated Due Date
• \( LMP \) — Last Menstrual Period (first day)
• \( 280 \) — Standard pregnancy duration in days (40 weeks)

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

3. Importance Of Pregnancy Dating

Details: Accurate pregnancy dating is essential for monitoring fetal development, scheduling prenatal tests, determining gestational age, and planning for delivery.

4. Using The Calculator

Tips: Enter the first day of your last menstrual period in the date field. The calculator will automatically compute your estimated due date based on NHS standards.

5. Frequently Asked Questions (FAQ)

Q1: Why Does NHS Use LMP Instead Of Conception Date?
A: LMP is more reliably remembered than conception date and provides a standardized method for pregnancy dating across healthcare providers.

Q2: How Accurate Is This Calculation?
A: This method is accurate for women with regular 28-day cycles. Ultrasound dating may be used to adjust the EDD if there are discrepancies.

Q3: What If My Cycle Is Not 28 Days?
A: For irregular cycles, the calculation may need adjustment. Consult with your healthcare provider for personalized dating.

Q4: When Should I Have My Dating Scan?
A: NHS typically offers a dating scan between 8-14 weeks of pregnancy to confirm the due date.

Q5: Can The Due Date Change?
A: Yes, the due date may be adjusted based on ultrasound measurements, especially if there's more than 5 days difference from LMP calculation.