Last Menstrual Period
Conception Date
Ultrasound Date
💡 This is the most common method. Enter the first day of your last period before conception.
💡 Use this if you know the exact date of conception (e.g., from IVF or known ovulation date).
💡 Use ultrasound measurements for the most accurate due date, especially in early pregnancy.
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Days Pregnant
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Days Remaining
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📊 Pregnancy Progress

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👶 Baby Development This Week

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🎯 Important Pregnancy Milestones

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📚 Due Date Calculator Information

How Due Dates are Calculated:

  • Naegele's Rule: Adds 280 days (40 weeks) to the first day of your last menstrual period
  • Conception Method: Adds 266 days (38 weeks) to the conception date
  • Ultrasound Method: Uses fetal measurements to estimate gestational age

Accuracy of Due Dates:

  • Only about 5% of babies are born exactly on their due date
  • Most babies (90%) are born within 2 weeks of the due date
  • First-time mothers often deliver 1-2 days past their due date
  • Ultrasound dating is most accurate when done before 20 weeks

Pregnancy Terms:

  • Full-term: 37-42 weeks
  • Preterm: Before 37 weeks
  • Post-term: After 42 weeks
  • Gestational age: Time since last menstrual period

Important Notes:

  • Due dates are estimates, not exact predictions
  • Natural variation in pregnancy length is normal
  • Multiple pregnancies (twins, triplets) often deliver earlier
  • Your healthcare provider may adjust your due date based on ultrasounds

⚠️ This calculator provides estimates for educational purposes. Always follow your healthcare provider's guidance for pregnancy monitoring and delivery planning.