To simplify this task, on almost every website devoted to the topic of pregnancy and childbirth, there is a special calculator where you enter your data and receive a number in response (gestation in weeks). Does it make it any easier? Does this figure answer the question, how many weeks does pregnancy last? Will she satisfy this young mother? Most likely, no, because she does not understand where exactly such a figure came from. For her, she is no different from the one that the obstetrician-gynecologist writes in the card.
First you need to understand how long a person's pregnancy lasts. All counted fairly accurately: 5600 hours, 280 days or 9 calendar months.
It would seem, to calculate the duration of pregnancy easily and simply, as well as determine the date of birth. So where is so much confusion? Some women are ready to argue hoarsely with doctors about the timing, proving that they know better how many weeks they have pregnancy, arguing that they remember the day of conception exactly.
Such confusion arises due to the fact that each participant in the dialogue chooses his point of reference. The woman is counting from the date of conception, because she knows exactly. But in this women are mistaken. The maximum that a woman can know for sure - the date when she had sex with her partner. And, I do not know, this is the date she equates to the date of conception.
To understand what is wrong, you need to understand the physiology of the process. The most favorable time for conception is the day of ovulation. On this day, a mature egg leaves the follicle. However, the movement of the egg through the fallopian tubes takes several days, and all this time it is suitable for fertilization. Spermatozoa can also exist in the female body for several days. Therefore, spermatozoa can get into the uterus in one day (it is his woman who considers the day of conception), and fertilize the ovule in another. So it turns out that the day of conception can not be determined, except that a woman will be constantly under the sights of powerful equipment.
That's why gynecologists count the gestation period in a different way. They count from the day when the woman started the last period. Usually this date is known to the woman exactly, which means that there is a tight binding to a specific date. This system of counting is called an obstetric term. It is not difficult to guess that with a standard cycle of 4 weeks, the difference between the actual period of pregnancy and obstetrics is about 14 days. How many weeks does pregnancy last for obstetric terms? The answer is simple - 40 weeks. The obstetric month is 28 days, this is the length of the average cycle of a woman. It is he who takes the starting point.
The last question remains: how does the term of pregnancy consider ultrasound specialists and why is it so often different from what gynecologists call? It's still easier. They do not consider him at all. The development of the fetus has long been prescribed for weeks, and the figure in the protocol of ultrasound indicates the stage of fetal development. That is, recording with this or that period means that your baby's development is exactly this term. The task of your doctor to compare the estimated time and development and determine whether it is normal in your case, is ahead of the curve, or slowed down.
A unified system for calculating the timing, linked to an exact date, is necessary so that the gynecologist can compare the gestational age and the level of development of the fetus to understand how well the pregnancy is going, whether there are pathologies or developmental delays. Therefore, it makes no sense to argue with your doctor about how many months you have pregnancy, because, firstly, the term of pregnancy is a conventional concept, and secondly, it does not allow you to determine the exact date of birth. It only helps to imagine in what period the baby's appearance is expected. And it makes a big difference how many weeks pregnancy lasts, no.