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 we calculate?

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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.