How to Use the Pregnancy Due Date & Trimester Calculator
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1
Enter the first day of your Last Menstrual Period (LMP) and your typical menstrual cycle length (default 28 days).
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2
Or enter the exact conception date if known.
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3
The calculator computes your Estimated Due Date (EDD) and current gestational age in weeks and days.
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4
Review the trimester timeline progression milestones (Trimester 1, 2, and 3 dates).
Practical Example & Use Case
Common Real-World Scenario
Entering an LMP of January 1 on a 28-day cycle calculates an Estimated Due Date of October 8 via Naegele’s rule (LMP + 1 year - 3 months + 7 days).
Technical Notes & Limitations
Browser Engine Architecture
Calculates clinical 40-week gestational age; actual labor onset varies naturally around the estimated date.
Frequently Asked Questions
What is Naegele's rule?
A standard obstetric formula: add 7 days to the first day of the last menstrual period, subtract 3 months, and add 1 year.