MedicPulse
MedicPulse

Estimated Due Date (EDD)

Calculates the Estimated Due Date (EDD) using the adjusted Naegele's Rule (LMP and cycle length) and applies ACOG Committee Opinion No. 700 guidelines to optionally re-date the pregnancy based on ultrasound biometry.

The Estimated Due Date (EDD) calculation is a fundamental obstetric assessment designed to establish a precise chronological baseline for pregnancy, essential for scheduling prenatal care, monitoring fetal growth, and planning delivery.

Medical Specialty:
Obstetrics

Patient Data

. Select the date for First Day of Last Menstrual Period (LMP).
. Enter the value for Cycle Length (Days) in units.

Ultrasound Dating (Optional)

. Select the date for Date of Ultrasound.
. Enter the value for Gestational Age at USG (Weeks) in units.
. Enter the value for Gestational Age at USG (Days) in units.

Fill in all required fields to see the result

FOR PROFESSIONAL USE ONLY

This calculator is a support tool intended exclusively for health professionals. It does not replace clinical judgment. The final decision regarding diagnosis and treatment is the sole responsibility of the professional.

About this Calculator 💡

The Estimated Due Date (EDD) calculation is a fundamental obstetric assessment designed to establish a precise chronological baseline for pregnancy, essential for scheduling prenatal care, monitoring fetal growth, and planning delivery. This tool provides a comprehensive EDD estimation by integrating both clinical data and ultrasound biometry.

Initially, it establishes a clinical baseline using an adjusted Naegele's Rule, calculating from the first day of the last menstrual period (LMP) while automatically correcting for cycle lengths that deviate from the standard 28 days. Because clinical estimation is often limited by irregular cycles or imperfect recall, the calculator also incorporates ultrasound dating.

Following ACOG Committee Opinion No. 700 guidelines, the tool automatically compares the clinical and ultrasonographic estimates to set the final definitive EDD, replacing the LMP-based date with the ultrasound date only if the discrepancy in days exceeds the acceptable gestational age-specific thresholds

Reference Values

  • •Final EDD based on LMP. Ultrasound biometry is recommended to confirm or adjust this clinical estimate.
  • •Final EDD based on Ultrasound. According to ACOG guidelines, the discrepancy between LMP and Ultrasound exceeded the acceptable threshold, making the Ultrasound date preferred.
  • •Final EDD based on LMP. The Ultrasound dating confirms the LMP date within the acceptable ACOG threshold.

Formula

Calculation Methodology Initially calculates the Estimated Due Date (EDD) using the LMP, adjusted for the patient's cycle length. If ultrasound dating is provided, the tool calculates a secondary EDD and compares the discrepancy. Following ACOG guidelines, the Ultrasound EDD automatically replaces the LMP EDD if the difference exceeds gestational age-specific thresholds (e.g., >5 days discrepancy before 9 weeks, or >7 days between 9-15 weeks).

Reference

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