Naegele's rule

Naegele's rule is a standard method of estimating the due date for a pregnancy. The rule estimates the expected date of delivery (EDD) by adding one year, subtracting three months, and adding seven days to the first day of a woman's last menstrual period (LMP). The result is approximately 280 days (40 weeks) from the start of the last menstrual period. Another method is by adding 9 months and 7 days to the first day of the last menstrual period.

History

Naegele's rule is named after Franz Karl Naegele, a German obstetrician who practiced in the mid-19th century. However, the method was first described by a Dutch physician, Hermann Boerhaave, in 1744. Naegele was the one who popularized the rule in the medical community.

Calculation

The calculation of the EDD using Naegele's rule assumes a regular menstrual cycle length of 28 days with ovulation occurring on the 14th day and is calculated from the first day of the LMP. If the woman's menstrual cycle is not 28 days, the estimated due date can be adjusted based on the known cycle length.

Accuracy

The accuracy of the EDD calculated by Naegele's rule is dependent on accurate recall by the mother of her last menstrual period. There is evidence to suggest that the accuracy of the EDD decreases the further into pregnancy the calculation is made.

See also

• Pregnancy
• Obstetrics
• Gestational age
• Estimated date of delivery

References

Naegele's rule Resources
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