Naegele’s rule explained: LMP + 280 days (and what it assumes)

Use these tools while you read—keep the same LMP or ultrasound anchor your clinician documented.

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Naegele’s rule is the famous LMP + 280 days shortcut taught on pregnancy wheels.

It assumes a 28-day cycle with ovulation near day 14—helpful as a default, misleading if your ovulation is consistently different.

Pair rule knowledge with ultrasound policies so you understand why your hospital letter might differ from a quick app tap.

Movement counting in the third trimester is not a competitive sport. Follow the cadence your team recommends rather than arbitrary internet counts, and escalate promptly when patterns change suddenly.

If you are pregnant after loss, some educational milestones feel emotionally loaded. It is okay to mute week-by-week apps and rely more on direct clinician reassurance until anxiety feels manageable again.

This article is educational. It does not diagnose, treat, or triage emergencies. Always follow your licensed obstetric clinician, midwife, or local emergency guidance.