Naegele Pregnancy Due Date
Naegele Pregnancy Due Date - a deterministic tool in Sophie Well's Clinical Math & Conversions group.
Open the Naegele Pregnancy Due Date → Runs in your browser. No signup, no tracking.
What this is
Compute the estimated date of delivery from the first day of the last menstrual period using Naegele's rule: LMP + 280 days (40 weeks). Sophie Well returns the EDD plus the current gestational age in weeks and days, assuming a regular 28-day cycle and ovulation on day 14.
When to use it
Use this for an initial pregnancy-dating estimate when only the LMP is known. First-trimester crown-rump-length ultrasound is more accurate and should override Naegele if the dates differ by more than 5-7 days (ACOG/SMFM Committee Opinion 700); for IVF pregnancies, transfer-date dating supersedes both.
References
Naegele rule: due date = LMP + 280 days.
Worked example: Due date 2025-10-08
Sophie Well is a reference and educational tool. Not medical, legal, or financial advice. Does not replace clinician judgment, professional billing review, or legal counsel.