BirthHow to Calculate Your Due Date

How to Calculate Your Due Date

How do I know my due date? How is it calculated? We discover how you can easily know it, knowing the probable day to give birth.

When a woman confirms that she is pregnant, one of her first concerns is usually when the baby will be born. Although only 5% of babies are born on the due date indicated by the calendar, it does not hurt to get an idea, even if it is approximate.

Pregnancy is counted by weeks, so there are those who consider that instead of talking about a specific day as the probable date of delivery, it made more sense to establish a certain week.

Formula to calculate probable due date

The first thing to take into account is the duration of a pregnancy: 40 weeks, or, what is the same, 280 days. This period of time is counted from the first day of the last menstruation. If the fertilization of the ovum is evaluated, the pregnancy lasts 38 weeks.  However, as it is difficult to know exactly when the fertilization was, the first day of the last menstruation is taken into account.

There is a very simple formula through which the probable date of delivery can be known;  it is known as Nagele’s Rule and it is taken into account by pregnant women, and even gynecologists, from all over the world. You simply have to subtract three months and add a total of seven days to the first day of the last menstruation; thus, the result is that probable due date.

Here is a simple example of how this calculation is done. If a woman has her last period on April 13, subtract three months and add seven days to this date; therefore, the due date is January 20.

As has been pointed out, pregnancy is measured by weeks; therefore, gestation is considered to have come to an end between weeks 38 and 42; therefore, the range is no more and no less than four weeks in which the baby can be born.

It is worth doing the calculation following the Nagele rule to know the expected due date.  Although very few babies are born that day, it is good to get a slight idea. However, who determines the specific gestational age is the gynecologist after performing the first ultrasound, in which he takes the measurements of the fetus.

Symptoms of childbirth

As we already mentioned in the article about am I in labor? Symptoms that indicate that labor is approaching, it is said that when a woman is in labor, she knows it.  However, it never hurts to know the symptoms that indicate that the baby is imminent. They are as follows:

  • Contractions: one of the warning signs that is repeated in practically all cases is that the contractions are stronger and, in addition, they happen more frequently, between approximately 10 and 20 minutes. Contractions progressively increase in both duration and intensity.
  • Mucous plug: another of the symptoms that indicate that labor is about to begin is the expulsion of the mucous plug; it is a small amount of mucous discharge that is quite thick during pregnancy and has remained sealed in the cervix.
  • Breakage of the water source: it is the most well-known symptom of all, and it occurs in absolutely all pregnant women. It occurs when the amniotic sac, which is filled with fluid that covers the baby, ruptures. This fluid is eliminated through the vagina and is the main indication that the baby is about to be born.

These are the indications that are worth taking into account during pregnancy; it is very important to know how to detect the symptoms that labor is imminent. As for the probable due date, it is important to take it for what it is; a probable date. Therefore, if it arrives, and even a few more days pass, and the baby has not yet been born, do not lose your cool.


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