# Question: What is Naegeles rule and how is it calculated?

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Naegeles rule involves a simple calculation: Add seven days to the first day of your LMP and then subtract three months. For example, if your LMP was November 1, 2017: Add seven days (November 8, 2017). Subtract three months (August 8, 2017).

## How many weeks is Naegeles rule?

Naegeles rule 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. Naegeles rule is named after Franz Karl Naegele, the German obstetrician who devised the rule.

## Why we add 7 days in Naegeles rule?

Adding 1 year and 7 days would bring you to June 16, 2011, as your estimated due date. This 3-step method is referred to as Naegeles Rule and is based on a normal 28-day menstrual cycle. Therefore, dates may have to be adjusted for longer or shorter menstrual cycles.

## How accurate is Naegeles rule?

The estimate of the 40-week duration has been widely accepted by clinicians and patients for over 200 years, despite criticism of the formula. The rule has served well over the years. A 1967 study by Treloar et al. of 2965 pregnant women reported that 70% of all live births occurred within 280 ± 10 days of their LMP.

## How do you use the Naegeles rule?

Naegeles rule involves a simple calculation: Add seven days to the first day of your LMP and then subtract three months. For example, if your LMP was November 1, 2017: Add seven days (November 8, 2017). Subtract three months (August 8, 2017).

## How do I calculate my gestation period?

Gestation by LMP is calculated from the first day of the last menstrual period. Gestation by CRL is calculated: Weeks = 5.2876 + (0.1584 * Crown_Rump_Length) - (0.0007 * Crown_Rump_Length2). This will be gestation at time of ultrasound. Gestation by BPD is calculated using the formula: Days = 2 * BPD + 44.2.

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