How due date is calculated

When you become pregnant once you get to do math to know when your baby is born, what will be the appointed day. Although the percentage of babies who are born the day that marks the calendar is very low, only 5 per cent, to know the probable date of birth will help you to have an indicative date.

calculated due date

Since pregnancy is counted in weeks, some believe that rather than a particular day would make more sense to talk about a probable delivery week. If you want to know when to get out of accounts we show how due date is calculated.

Duration of pregnancy
The approximate duration of a pregnancy is 280 days. Calculated 40 weeks from the first day of the last menstrual period (LMP) or 38 weeks (approximately nine months) from the time that the ovum is fertilized, which in a regular period ovulation usually take place 14 days after menstruation occurs.

As all women know the time of ovulation and because it is impossible to know exactly the date when conception occurred, the date taken into account to calculate the due date is the first day of the last menstruation.

Naegele’s rule
You can do a simple calculation to know your due date (FPP): a formula known as Naegele’s rule. It is to subtract three months and add seven days to the first day of your last period. The result is the due date.

For example, if your last period was January 1, you have to subtract three months, and add seven days: the due date is October 8.

Calendar of due date
The gynecologists in their inquiry usually use a calendar wheel to calculate the due date and gestogram to know the dimensions and weight of the fetus during pregnancy, week by week.