How to correctly calculate the gestational age?

2024 Author: Priscilla Miln | [email protected]. Last modified: 2024-01-15 22:35

It is extremely difficult to calculate the gestational age by weeks and days with maximum accuracy. Some specialists use ultrasound to track the period of ovulation. However, this method is used only if a woman is suspected of infertility. Accordingly, it can be assumed that the solution of the problem set up to a day is practically impossible. For both doctor and future parents.

But there are a number of methods by which you can independently calculate the date of conception.

Calendar calculation option

When a woman has sexual intercourse irregularly, it is much easier to determine the time period when fertilization occurred. In such a situation, the expectant mother can almost accurately determine when the fastest spermatozoon has reached its goal.

As an alternativeAn option is the ability to use basal temperature charts if a woman records such readings with a certain frequency. The received date must be reported to the doctor after the pregnancy is confirmed. As a rule, the doctor adds about two weeks to the date of the last period.

This is due to the fact that another indicator for calculations is important for the observing doctor - the term of obstetric pregnancy. Its indicators depend on the dates of the first and last day of menstruation. In this regard, it may seem that doctors begin to count the gestational age at the onset of the first day of the menstrual cycle, which is not true. However, this method of calculation is the most accurate. This method of calculating the gestational age by weeks can also be used to calculate the expected date of birth. To do this, add 280 days to the date of the onset of menstruation.

Another way is to use Naegele's formula. You need to subtract 3 months from the date of the last period, and then add 7 days.

When the period of ovulation is determined exactly, you can add 264 days to the first day of your last period. As a result, the approximate date of the onset of labor activity will be determined. However, you will have to deal with such a calculation yourself, since doctors do not use this technique. A woman can independently calculate the gestational age by the date of menstruation using the above information.

Ultrasound

Modern equipment makes it possible to calculate the timepregnancy on ultrasound. Ultrasound examination is no longer know-how for anyone, as it has been used for many years. With its help, you can not only check the state of fetal development, but also clarify data on gestation. The results of studies are most accurate when the gestational age is less than eight weeks. This is due to the fact that in the absence of any deviations, the development process of each embryo occurs in the same way. By the size of the fetus, you can calculate the gestational age by weeks as accurately as possible.

It is important to take into account the fact that the number of errors also increases with the increase in the term. This is due to the manifestation of individual signs of development. One embryo may have a larger head, the other may have parameters slightly smaller than the established limits, which is not a serious deviation.

As a rule, indicators with a lag or lead within a week are recognized as insignificant. This is the norm, so no treatment is prescribed. The terms of pregnancy are in any case approximate and are established on the basis of measurements of the coccygeal-parietal region.

In the event that there is no possibility of making an error with the definition of the week of gestation, but the size of the fetus is more than 14 days behind, the observing specialist can make a diagnosis of intrauterine growth retardation. Unfortunately, such a case is not treatable. As for the activities that are carried out in the hospital, it is rather prevention. Therefore, it is important to move as much as possible, eat only he althy food, and not be nervous or carry heavy weights.

Examination by a specialist

Most women, as soon as they discover a delay, rush to make an appointment with a gynecologist to check their suspicions. However, by means of an ordinary examination, it is impossible to determine the fact of pregnancy for sure. An increase in the uterus can be before the onset of menstruation. Active growth of the uterus is observed only at the end of the first trimester. The 5th and 6th weeks of pregnancy (usually the 2nd or 3rd week of delay) are characterized by sizes that exceed the normal parameters of the uterus. Visually, it can be compared with the size of a chicken egg. On the eighth week, the parameters increase to a goose egg, and on the 10th week it can be compared to a woman's fist. You can calculate the gestational age more accurately in the first trimester.

First stirring

Many gynecologists say that the expectant mother should listen to her feelings and be sure to remember the date when she felt the first movement of the baby. After all, in this way you can calculate the gestational age. According to statistics, the first fetal movements appear on the 20th week. With repeated pregnancy - on the 18th. The date of movement must be included in the woman's medical record, as it is also taken into account when determining the period of labor.

According to the reviews of many mothers, the established terms of pregnancy may not always coincide with the expected ones, since in the third trimesterthe fetus may show individual signs of development within the normal range. Also, do not worry overly responsible mothers who are afraid to miss the first movements, so as not to mislead the doctor when calculating the gestational age. Doctors play it safe and analyze the indicators of ultrasound and dopplerometry. In addition, the first movements are rather weak, but you can still feel them. If a woman lies on her back, then it is impossible not to notice the movement.

Along the length of the uterus

With the onset of the second trimester, many doctors begin to evaluate the parameters of the fetus by measuring the length of the uterus. To do this, use an ordinary centimeter tape. Every week this figure should increase by an average of a centimeter. There is an alternative option for determining parameters using ready-made tablets, which are often used by doctors:

Parameter in weeks	Characteristic
12	The uterus is located in the upper part of the womb
14	The position of the uterus becomes two fingers higher
16	Sensation of the bottom of the uterus in the space between the womb and the navel
20	The bottom is two fingers below the navel
24	The position of the uterus is compared to the navel
28	Location of the bottom two fingers above the navel
32	Location between the xiphoid process and the navel. Length up to 30cm
36	The xiphoid process is at the level of the fundus of the uterus
40	Before labor begins, uterine position as before 32 weeks

The parameters and volume of the abdomen also matter, but in order not to be mistaken, this factor can only be taken into account in conjunction with others, it will not be able to show the gestational age with an accuracy of up to a week. Volume should be measured at the level of the navel.

If a woman is not obese, then the average abdominal volume at the 32nd week reaches 85 cm. Shortly before the onset of labor, the volume increases to 100 cm. This is due to the fact that the child begins to gain weight as quickly as possible.

With a constant measurement of the length of the uterus, you can make sure that the development of the fetus is normal. If pathological processes occur, this criterion will help prevent the development of complications.

Heart Tones

The first heartbeat is monitored at 4 or 5 weeks. This is the second or third week of the delay in menstruation. When visiting a planned ultrasound, you can hear a heartbeat, as well as make sure that the fetus is alive and developing normally. At a later date, the heartbeat can be determined by the doctor through the outer uterine wall using a special apparatus. However, the tones are traced somewhatlater, at 10-12 weeks. A little later, you can already track the movements.

To check the heartbeat, the attending physician uses a stethoscope at a later date. This is a special device that is applied with one end to the belly of a pregnant woman, and with the other to the doctor's ear. Visually, it resembles an ordinary tube. Sometimes hearing a heartbeat is quite difficult for some reason. So, for example, the placenta, due to its location near the outer wall, can muffle the sound, or the cause can be a dense fatty layer. However, this is not considered a threat or pathology. Among the serious causes that need to be monitored is hypoxia or polyhydramnios. With increasing gestational age, the heartbeat should be heard more clearly.

hcg

A method used primarily in the early stages. However, the error still exists. To determine the level of chorionic gonadotropin, it is necessary to take blood for analysis from a vein. As for the approximate results (in honey / ml), they are as follows:

• second week - 25/300;
• third - 1500/5000;
• fourth – 10,000/30,000;
• fifth - 20,000/100,000.

These values show that the results obtained have a wide range, which means that there is a possibility of making mistakes. Therefore, it is more expedient to use this method not to calculate the gestational age by day, but to establish the very fact of pregnancy.

It is important to note that the level of hCG in the normal development of gestation should increase daily. This is due to the fact thatthe production of this hormone occurs exclusively with the development of pregnancy.

Calculation based on ovulation

When the egg is released from the follicle, ovulation occurs. During this period, fertilization by sperm can occur. For women planning a pregnancy, this period is of great importance, since with its definition it is possible to plan the birth of a child. You can determine ovulation in several ways:

1. Using special tests that can be bought at the pharmacy. Many of them are highly reliable
2. If the cycle is regular, there are no failures, then the ovulation period can be set by measuring the basal temperature.
3. Also, small changes in secretions also indicate the onset of ovulation. They become more viscous, their number also increases.

Normally, this period passes closer to the middle of the entire cycle. If its duration is stable and does not change, then the number of days of the cycle can be divided by two and the resulting value can be added to the beginning of the last menstruation. This is an effective way to calculate the gestational age by conception.

Using an online calculator

Modern technical capabilities help to avoid manual calculations. In this case, online calculators or special applications for electronic gadgets will help. Their use does not involve any difficulties. To get started you needindicate the date of the probable beginning of menstruation in the format day, month and year. Next, click on the start calculation button. The following information should appear in automatic mode:

1. Approximate date of onset of labor.
2. Approximate number of days left until delivery.
3. What week of pregnancy is the woman and what is the trimester.
4. Estimated date of conception.

This method is similar to the method of how to calculate the gestational age by menstruation.

Basal Temperatures

Thus, you can calculate the gestational age at the initial stage. The temperature is measured in the anus. As a rule, before the onset of the ovulation period, its indicator should be within 37 ^oC. After the egg is released, the temperature drops sharply and then rises to 37.2 ^{oC. This is due to the fact that the level of hormones changes dramatically.}

According to the recommendations of doctors, it is necessary to monitor these parameters for four months. This will make it possible to establish the threat of miscarriage in time and preserve the he alth of the woman. This will be evidenced by an unplanned sharp drop in temperature. In the case when there is an excess of 37, 7 oC, we are talking about the development of the inflammatory process.

It is also important to take into account that it is best to measure the temperature in the morning - immediately after waking up. If hormonal drugs are prescribed, then during this period it should not be measured, the information will be unreliable. It should be noted that the constant measurement of temperature indicators in the anus helps to determine the gestational age as accurately as possible.

Observation by a doctor throughout all three trimesters is mandatory for all women expecting a baby. Timely determination and calculation of the gestational age will help determine the day of conception as accurately as possible, as well as the expected date of birth.