Calculation method
Naegele's rule: LMP + 280 days
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How is the due date calculated?
Naegele's Rule
Add 280 days (40 weeks) to the first day of your last menstrual period — the standard method used by doctors worldwide.
How accurate is it?
Only ~5% of babies arrive exactly on their due date. A normal pregnancy spans 37–42 weeks.
Can it change?
Yes — your doctor may adjust the date based on an ultrasound scan, especially if cycles are irregular.
Pregnancy Milestones
Pregnancy confirmed
Week 4
Baby's heartbeat detected
Week 8
End of 1st trimester
Week 12
Gender can be revealed
Week 16
Anatomy scan (halfway!)
Week 20
Viability milestone
Week 24
End of 2nd trimester
Week 28
Baby's lungs maturing
Week 32
Baby considered full-term
Week 36
Estimated due date
Week 40
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