Obstetrics
Estimated Due Date (EDD)
Calculates the Estimated Due Date (EDD) using Naegele's rule.
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Parameters
Estimated Due Date (EDD) Result
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Formula
Naegele's Rule: EDD = First day of LMP + 280 days (40 weeks).Clinical Pearls
Establishing an accurate EDD is essential for optimal prenatal care, scheduling screening tests, and timing of delivery.
Limitations
Naegele's rule assumes a standard 28-day menstrual cycle with ovulation occurring on day 14. First-trimester ultrasound is the most accurate method for establishing or confirming gestational age.