Pregnancy, duration and curiosity about the weeks of gestation

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Pregnancy, duration

As long as we don't get pregnant, we remain convinced that pregnancy lasts nine months. In fact, the famous "nine months" represent in the collective imagination the period in which a child grows up in the mother's womb and the woman lives the most extraordinary experience of life. But in reality this is not the case. The duration of pregnancy is not exactly nine months: let's see why.


Pregnancy begins, therefore, when a egg is fertilized by the sperm. The fertilized embryo moves to the walls of the uterus, where it will nest in a few days, and where it will then grow and develop week after week into a fully formed baby.

Read also: Weeks of Pregnancy

Why doesn't pregnancy last 9 months?

It takes approx 38 settimane from the day of conception to that of childbirth, and this period is not nine months: since very few women can tell when conception has occurred, then doctors simply count from the last menstrual cycle, thus adding 2 weeks to the 38 canonical ones. And so we arrive at 40 weeks.

Pregnancy is defined as:

  • full term when delivery occurs between 37 and 41 weeks
  • preterm (or premature birth) when delivery occurs before 37 weeks
  • protracted (beyond term) when delivery occurs at 42 weeks or beyond.

Duration of pregnancy from conception

It is really difficult to establish what was the exact day on which conception took place. The spermatozoa have a longer life than the egg: they can remain active in the fallopian tubes even for days and it is not possible to be sure of the exact day of ovulation or of the one in which fertilization took place, therefore to date the pregnancy it is necessary to use a obstetric rule, a wheel-shaped tool that allows you to calculate the expected date of delivery starting from the first day of the last menstruation and going on to 40 settimane (280 days). This is because women who have a regular menstrual cycle will most likely have ovulated fourteen days after their last period and conception will have occurred in those hours.

  • If you don't know when you conceived: Add 40 weeks from the date of your first day of your last period.
  • If you know when you conceived: add just 38 weeks from the date of conception.

Know that, in any case, the doctor will calculate 40 weeks from the beginning of the last menstruation.

How the belly grows in pregnancy

On average, weight gain between i 9 ed i 12 Kg. Not only the baby contributes to weight gain, but also amniotic fluid, placenta, fat deposits and the fact that tissues tend to retain a greater amount of fluid.

The belly in the first quarter is only slightly hinted at, then begins to show itself more clearly in the second quarter and finally grows exponentially in the third quarter. In the last fifteen days of pregnancy, the belly "lowers", the baby begins to prepare to be born and therefore the weight can be felt especially towards the pubic area.

How many weeks do you give birth on average

A physiological pregnancy ends between 37th and 42nd week, but only 1 in 20 women gives birth on the presumed date of birth: in the vast majority of cases, in fact, the date of birth can vary up to five weeks compared to the day established on the calendar. Even a study conducted by the National Institute of Environmental Health Sciences analyzed 125 pregnancies and concluded that only 4% of women give birth at the end of 280 days and only 70% of women give birth within 10 days of the presumed date of delivery.

Calculation of pregnancy

According to the World Health Organization (WHO)

the duration of gestation is measured from the first day of the last normal menstruation. Gestational age is expressed in full days or full weeks

For this reason, pregnancy is measured in weeks and not months.

41 weeks of pregnancy without contractions

Towards the end of pregnancy some checks will be carried out aimed at assessing the health and well-being of the child. The so-called "monitoring" (cardiotocography) is used to monitor the baby's heartbeat and the presence of any contractions.

Should the pregnancy last beyond 41 weeks, the gynecologist will evaluate the quality and quantity of the amniotic fluid and will detect the presence of fetal suffering to understand how to proceed and whether to deliver the baby with an induced birth or a caesarean section.

How do you know when the baby was conceived?

It is really difficult to establish with certainty when the conception took place. Even if you had only one sexual intercourse during the fertile period, this does not necessarily mean that fertilization took place on that day. How is it possible? Because the egg is able to survive for about 24 hours, while the spermatozoa can survive for up to five days. Conception, therefore, took place within this rather large time window.

How to count the weeks of pregnancy

As we have seen, therefore, pregnancy lasts 40 weeks from the beginning of the last menstruation to the presumed date of delivery and in the calculation of the weeks of pregnancy not only the weeks are considered, but also the days according to this table:

  • 1st month: starts from the first day of the last menstruation (0 weeks + 0 days) and ends at 4 weeks + 3 days
  • 2nd month: from 4 weeks + 4 days to 8 weeks + 5 days
  • 3rd month: from 8 weeks + 6 days to 13 weeks + 1 day
  • 4th month: from 13 weeks + 2 days to 17 weeks + 4 days
  • 5nd month: from 17 weeks + 5 days to 21 weeks + 6 days
  • 6nd month: from 22 weeks + 0 days to 26 weeks + 2 days
  • 7nd month: from 26 weeks + 3 days to 30 weeks + 4 days
  • 8th month: from 30 weeks + 5 days to 35 weeks + 0 days
  • 9th month: from 35 weeks + 1 day to 40 weeks + 0 days

Duration of pregnancy of an elephant and other animals

How long are pregnancies in the animal world and which are the longest pregnancies? Here are some curiosities.

The longest pregnancy is that ofelefantessa which takes 22 months to deliver her puppy, but also that of the Rhino it is not a trivial matter because it can last up to 18 months.

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