Gestational Age Calculator (Naegele's Rule)

When it activates

Scribeable activates a calculator from the encounter. The Gestational Age Calculator (Naegele's Rule) can activate when the transcript or pasted chart context documents any of these:

• Pregnancy dating
• Gestational age calculation
• Due date estimation

Inputs the note needs

1 input. Each is resolved from the transcript, the pasted chart context and charted labs; at this calculator’s tier a missing input is never requested, and a missing required input keeps the score out of the draft.

Scoring

EDD = LMP + 280 days. Gestational age = (today - LMP) / 7 weeks.

Interpretation

Accuracy best when LMP is certain and cycles regular. Ultrasound dating preferred if discrepancy >7 days in first trimester, >14 days in second trimester.

Evidence

Sources carried in Scribeable's citation registry for this calculator; guideline version: Naegele's Rule.

• Naegele FC. Lehrbuch der Geburtshilfe (Naegele's Rule for estimated due date)Naegele's Rule · 1830 · link last verified 2026-03-28

How Scribeable handles it in the note

When an encounter activates the Gestational Age Calculator (Naegele's Rule) (its highest tier is recommended), Scribeable does not ask you for missing inputs. The score is computed in code from whatever inputs resolve from the transcript, the pasted chart context or charted labs; a computed value is written into the draft only when every required input already resolves.

The score is computed in code from the resolved inputs, not recalled by the language model. A stated Gestational Age Calculator (Naegele's Rule) value is compared against the computed one when the draft's structured summary carries it; a disagreement found there is flagged to the second drafting pass, which is instructed to correct the score and its interpretation, unless Scribeable has supplied the computed value to that pass, in which case the value the draft writes is checked against the supplied one and a detected difference is shown beside the note for you to adjudicate rather than silently rewritten.

Classified as a risk score: activated strictly, by a documented trigger, never by a permissive reading of the encounter.

Related calculators

• Edinburgh Postnatal Depression Scale (EPDS)Screens for perinatal depression to identify patients needing further evaluation and treatment
• APGAR ScoreRapidly assesses newborn clinical status at 1 and 5 minutes after birth to guide resuscitation decisions
• ASA Physical Status ClassificationClassifies patient physical status prior to anesthesia to stratify perioperative risk and guide anesthetic planning
• BI-RADS (Breast Imaging Reporting and Data System)Standardizes breast imaging assessment and management recommendations to ensure consistent reporting and follow-up
• Bishop ScoreAssesses cervical readiness for labor induction to predict likelihood of successful vaginal delivery
• CDC Wound ClassificationClassifies surgical wounds to predict surgical site infection risk and guide antibiotic prophylaxis

Can activate in: Primary Care, OB/GYN.