To estimate the Expected Date of Delivery (EDD), how many days should be added to the first day of the last menstrual period (LMP)?

Correct option is C

According to Naegele’s Rule, the expected date of delivery (EDD) is calculated by adding 9 months and 7 days to the first day of the last menstrual period (LMP). The average pregnancy lasts 280 days (40 weeks).
Explanation of Each Option:
• (a) 9 months: Incomplete formula, missing additional days. Pregnancy duration is not counted in exact months but includes extra days based on the last menstrual period (LMP).
• (b) 9 months 2 days: Incorrect; standard calculation adds 7 days. Naegele’s Rule requires adding 7 days to the LMP date before subtracting 3 months.
• (c) 9 months 7 days: Correct answer; follows Naegele’s Rule. This method estimates the expected date of delivery (EDD) by adding 7 days and subtracting 3 months from the LMP, ensuring accuracy.
• (d) 9 months 14 days: Overestimates pregnancy duration. Adding 14 days results in an extended gestational period beyond the standard 280 days.