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Understanding Pregnancy Due Date Calculation
Formula
Naegele's rule estimates the due date as 280 days (40 weeks) from the first day of the last menstrual period (LMP). This assumes a 28-day cycle; adjustments are made for longer or shorter cycles.
Only about 5% of babies are born on their exact due date. Most are born within two weeks before or after. The due date is an estimate used for prenatal care planning, not a precise prediction.
Common use cases:
- Prenatal care planning
- Tracking pregnancy milestones
- Maternity leave scheduling
Frequently Asked Questions
Dr. David Park
Applied Mathematician, PhD Mathematics
David holds a PhD in Applied Mathematics from MIT. He has published research on numerical methods and computational algorithms used in engineering and scientific calculators.
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