In-depth guide

Due date estimates from LMP: what obstetric timelines assume

Guidelines commonly add 280 days (40 weeks) to LMP when cycles are regular ~28 days. Irregular cycles, IVF dates, and early ultrasound measurements change the clinical picture.

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Why LMP works only sometimes

Ovulation day shifts with cycle length. If you ovulate later than day 14 of a nominal cycle, LMP-based estimates skew early unless adjusted.

FAQ

Is this professional advice?
No—educational estimates only.
Why might numbers differ from another app?
Rounding, assumptions, and unit conventions vary.
Can I rely on this for legal or medical decisions?
No—consult qualified professionals.

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