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Pregnancy Due Date Calculator

Estimated due date from last menstrual period.

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Author Franz Naegele

First Published 1830

Evidence Standard obstetric practice

Category Obstetrics

Original Study Naegele's rule: LMP + 7 days - 3 months + 1 year

About Naegele's rule estimates the estimated date of delivery from the first day of the last menstrual period, assuming a 28-day cycle.

Clinical Use Initial EDD estimation. First-trimester ultrasound supersedes LMP-based dating.