Why are 2 weeks added to conception date?
If your period is regular and lasts 28 days, and if ovulation generally happens on day 14 of your cycle, then conception probably took place about two weeks after the LMP. For gestational age counting, these two weeks are added to a pregnancy as a simpler method than trying to track from ovulation or fertilization.
How is Naegele’s rule calculated?
Naegele’s 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 Naegele’s rule?
Background: The proposition that a pregnancy is 40 weeks or 280 days in duration is attributed to the German obstetrician Franz Naegele (1778-1851). His rule adds nine months and seven days to the first day of the last menstrual period.
What affects Naegele’s rule?
However the unequal length of the Gregorian calendar’s months results in Naegels’s rule overestimating the EDD by 3 days for all LMPs in May, and depending on the effect of leap years gives precise dates on only either 2, 5 or 7 months of the year. The rule assumes 40 weeks, or 280 days from LMP.
Are you pregnant from the day you conceive?
While it’s possible that you could conceive within minutes of sexual intercourse, it’s more likely to take place hours or even days after you have intercourse. You aren’t officially pregnant until the day that an egg is fertilized and implants into the uterus.
What is the purpose of Naegele’s rule?
Naegele’s rule is a standard way of calculating the due date for a pregnancy when assuming a gestational age of 280 days at childbirth. The rule estimates the expected date of delivery (EDD) by adding a year, subtracting three months, and adding seven days to the origin of gestational age.
Why is Naegele’s rule important?
Because ovulation is not an easily observed event, using Naegele’s rule provides an indirect measure of conception and remains the current standard for calculating the EDD based on the first day of the LMP.