Pregnancy Due Date Calculator

Find Out When Your Baby Is Due

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Estimated Due Date

-- weeks pregnant

1st Trimester 2nd Trimester 3rd Trimester

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Key Pregnancy Milestones

  • Conception Date (estimated) --
  • End of 1st Trimester (Week 12) --
  • Anatomy Scan (Week 18-20) --
  • Viability (Week 24) --
  • End of 2nd Trimester (Week 26) --
  • Full Term (Week 37) --
  • Due Date (Week 40) --

How Is Your Due Date Calculated?

Your estimated due date (EDD) is calculated using Naegele's Rule, a standard method used by healthcare providers worldwide:

  • From Last Period (LMP): Add 280 days (40 weeks) to the first day of your last menstrual period
  • From Conception: Add 266 days (38 weeks) to your conception date

The calculation assumes a 28-day menstrual cycle with ovulation occurring on day 14. If your cycle is longer or shorter, the due date is adjusted accordingly.

Understanding the Trimesters

First Trimester (Weeks 1-12): Your baby's major organs and systems begin to form. This is when many women experience morning sickness. It's important to start prenatal vitamins with folic acid.

Second Trimester (Weeks 13-26): Often called the "honeymoon period" as morning sickness typically subsides. You'll likely feel your baby's first movements (quickening) around weeks 18-20. The anatomy scan is usually done during this time.

Third Trimester (Weeks 27-40): Your baby gains weight rapidly and prepares for birth. You may experience Braxton Hicks contractions. Regular check-ups become more frequent.

Important Pregnancy Milestones

  • Week 8: First prenatal appointment typically scheduled
  • Week 10-12: First trimester screening available
  • Week 12: Risk of miscarriage significantly decreases
  • Week 18-20: Anatomy scan (mid-pregnancy ultrasound)
  • Week 24: Viability milestone - baby has a chance of survival if born early
  • Week 28: Glucose screening test for gestational diabetes
  • Week 37: Baby is considered "early term" and lungs are typically mature
  • Week 39-40: Full term - ideal time for delivery

How Accurate Is This Calculator?

While due date calculators use medically accepted formulas, only about 5% of babies are born on their exact due date. Most babies arrive within a two-week window before or after the estimated date. Your healthcare provider may adjust your due date based on:

  • First-trimester ultrasound measurements (most accurate)
  • Second-trimester ultrasound
  • Irregular menstrual cycles
  • IVF or assisted reproduction dates

Frequently Asked Questions

How is my due date calculated?

Your due date is calculated using Naegele's Rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP). If you know your conception date, add 266 days (38 weeks). The calculation assumes a 28-day cycle with ovulation on day 14.

How accurate is the due date calculator?

Due date calculators provide an estimate. Only about 5% of babies are born on their exact due date. Most babies arrive within 2 weeks before or after. Your healthcare provider may adjust your due date based on ultrasound measurements, especially in the first trimester.

What are the three trimesters of pregnancy?

First Trimester (Weeks 1-12): Baby's organs begin forming. Second Trimester (Weeks 13-26): Baby grows rapidly, you may feel movements. Third Trimester (Weeks 27-40): Baby gains weight and prepares for birth.

When should I see a doctor after a positive pregnancy test?

Schedule your first prenatal appointment around 8 weeks after your last period. Contact your doctor sooner if you experience severe pain, heavy bleeding, or have a history of complications. Early prenatal care is important for a healthy pregnancy.

Medical Disclaimer: This calculator provides an estimated due date for informational purposes only. It should not replace prenatal care or medical advice. Always consult your healthcare provider for accurate dating and personalized pregnancy care. Contact your doctor immediately if you experience any concerning symptoms.

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