Pregnancy Calculator
Estimates gestational age from LMP. Standard pregnancy is 40 weeks from LMP assuming 28-day cycle.
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How It Works
Estimates gestational age from LMP. Standard pregnancy is 40 weeks from LMP assuming 28-day cycle.
Quick Reference
Weeks 1-12
First trimester
Embryo develops
Weeks 13-26
Second trimester
Fetus grows rapidly
Weeks 27-40
Third trimester
Baby prepares for birth
Tips & Shortcuts
First trimester ultrasound is more accurate than LMP.
Only 5% of babies arrive on exact due date.
Common Mistakes
Planning around exact due date
Normal delivery is 37-42 weeks. Due date is estimate only.
Not adjusting for irregular cycles
Longer cycles push due date later. Shorter push earlier.
Frequently Asked Questions
Only 4% of babies are born on their exact due date. About 60% arrive within 1 week and 90% within 2 weeks.
Gestational age counts from the first day of your last period (LMP) and is used by medical professionals. Fetal age counts from conception — about 2 weeks less.
First trimester: weeks 1–12. Second trimester: weeks 13–26. Third trimester: weeks 27–40. Full term is 37–42 weeks.
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