The first thing we want to know after finding out that we are pregnant is to know the date our baby will be born , or when we get out of business. This is known as the probable delivery date (PPD), which is calculated from the first day of the last menstruation, or date of the last menstruation (LMP).
This date is calculated using Naegele’s Rule, which consists of subtracting three months from the first day of your last menstrual period, and then adding seven days. The result is your due date.
For example, if the date of your last period was February 1, 2021, we subtract three months to know the month (November 1) and add 7 days to know the probable delivery date (FPP), which will be the 8th of November 2021.
The pregnancy calculator that you can see below is based on this data, and will give you the result that it would give you if you did the formula.
How the pregnancy calculator works
It is a simple online application in which you must enter the date of the first day of your last menstruation. Once noted, the pregnancy calculator gives you the expected due date and the day of the week .
How to calculate pregnancy weeks
The first day of the date of your last menstruation is the day when the weeks of gestation begin to be counted. Week 1 is the starting point of pregnancy. From there, 40 weeks (280 days of gestation) are counted, or 38 weeks from the moment of fertilization.
As in most women it is not possible to calculate the exact day of ovulation, the first day of the last menstrual period is taken as the date of the beginning of the pregnancy .
The gestiogram or pregnancy wheel is another tool that allows you to know the probable date of delivery, as well as the weeks of gestation, the weight and the size of the baby.
In any case, as we have mentioned sometime in Babies and more, the probable due date should be called the unlikely due date, because very few women actually give birth on that day and therefore the results of the pregnancy calculator must always be taken as an approximation to the day of your new maternity and not as a “binding contract”.
Please note that this is an estimated date and is based on regular 28-day cycles. Your baby will most likely be born between two weeks before and after your due date.
Pregnancy week by week: from week 1 to week 40
The trimesters of pregnancy
Finally, as you know, in addition to weeks, pregnancy is divided into three trimesters .
- The first trimester of pregnancy ranges from fertilization to week 13.
- The second trimester of pregnancy spans from week 14 to week 27.
- The third trimester of pregnancy spans from week 28 to week 40.
In Babies and more | Calendar of measurements and weight of the fetus during pregnancy, week by week
