High Quality Content by WIKIPEDIA articles! Naegele's Rule is a standard way of calculating the due date for a pregnancy. It is named after Franz Karl Naegele (1778-1851), the German obstetrician who devised the rule. Franz Karl Naegele was born July 12, 1778, in Düsseldorf, Germany. In 1806 Naegele became ordinary professor and director of the lying-in hospital in Heidelberg. His "Lehrbuch der Geburtshilfe," published in 1830 for midwives, enjoyed a successful 14 editions. The rule estimates the expected date of delivery (EDD) (also called EDC, for estimated date of confinement) from the first day of the woman's Last menstrual period (LMP) by adding a year, subtracting three months and adding seven days to that date. This approximates to the average normal human pregnancy which lasts 40 weeks (280 days) from the LMP, or 38 weeks (266 days) from the date of fertilization.