Naegele’s Rule is a standard way of calculating 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 LMP.
LMP = 8 May 2009
+1 year = 8 May 2010
-3 months = 8 February 2010
+7 days = 15 February 2010
‘Naegele’s Rule’ is based on a 28 day menstrual cycle. The due date can be different if the woman’s menstrual cycle is not 28 days. For example if it was about 21 days the month you conceived, you would deduct 7 days from this date. If your cycle was about 35 days the month you conceived, you would add 7 days to this date……..!!