Health

Due Date Calculator: How to Calculate Your Pregnancy Due Date

How Due Dates Are Calculated


The most common method is Naegele's Rule:

Due Date = First day of last menstrual period (LMP) + 280 days (40 weeks)


Naegele's Rule Explained


1. Take the first day of your last menstrual period

2. Add 7 days

3. Subtract 3 months

4. Add 1 year


Example: LMP = March 1, 2025

Due Date: March 1 + 7 days = March 8, then back 3 months = December 8, 2025


Pregnancy Trimesters


First Trimester (Weeks 1-12):

  • Major organs begin forming
  • Morning sickness common
  • First prenatal visit

    • Second Trimester (Weeks 13-26):

  • Baby's movements felt
  • Gender can be determined
  • Anatomy scan at 18-20 weeks

    • Third Trimester (Weeks 27-40):

  • Rapid growth phase
  • Baby positions for birth
  • More frequent checkups

    • Factors That Can Affect Due Date


  • Irregular menstrual cycles
  • IVF conception (exact date known)
  • Ultrasound measurements
  • First-time vs subsequent pregnancies
  • Multiples (twins often arrive earlier)

    • Important Notes


  • Only about 5% of babies arrive on their exact due date
  • Full term is considered 39-40 weeks
  • Most babies arrive between 37-42 weeks
  • Always consult your healthcare provider for personalized guidance

    • Calculate Your Due Date


    Use our free due date calculator to estimate your baby's arrival date.

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