What it means
A quick calculation of the estimated date of birth (EDB or EDD), named after Franz Naegele, the German obstetrician who described it in the early 1800s. Take the first day of the last normal menstrual period, count back 3 months, add 7 days, and add a year if needed. It assumes a regular 28-day cycle, so an early ultrasound is often used to confirm or change the date.
For the nurse
Ask for the first day of the last normal period, not the last day, and whether cycles are regular. Pregnancy wheels and apps do the same math.
In a chart
"LMP June 10; by Naegele rule, EDD March 17."
At a glance
| Also written | Naegele's rule, Naegele’s rule, Nagele rule, Nägele's rule |
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Related terms
quickening
The first movements of the fetus that a pregnant person can feel.
fundal height
The distance in centimeters from the top of the pubic bone to the top of the uterus, measured during pregnancy.