1. What is the Pregnancy Due Date Calculation?

The pregnancy due date calculator estimates the expected date of delivery (EDD) based on the first day of your last menstrual period (LMP) plus 280 days (40 weeks). This is the standard method used in the UK healthcare system.

2. How Does the Calculator Work?

The calculator uses the Naegele's rule:

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.

3. Importance of Due Date Calculation

Details: An accurate due date helps monitor fetal development, schedule prenatal tests, and determine if pregnancy continues beyond term (post-term).

4. Using the Calculator

Tips: Enter the first day of your last menstrual period in the format YYYY-MM-DD. The calculator will add 280 days to this date.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is this calculation?
A: Only about 5% of women deliver on their exact due date. Most deliver within 2 weeks before or after.

Q2: What if my cycle isn't 28 days?
A: For irregular cycles, an early ultrasound scan provides more accurate dating.

Q3: When will I have my NHS dating scan?
A: In the UK, the dating scan is typically offered between 8-14 weeks of pregnancy.

Q4: Can the due date change?
A: Yes, your midwife may adjust it based on ultrasound measurements in early pregnancy.

Q5: What's considered full term?
A: Between 37-42 weeks. Babies born before 37 weeks are premature, after 42 weeks are post-term.