How to determine the gestational age: the most accurate ways

2024 Author: Priscilla Miln | [email protected]. Last modified: 2023-12-16 00:21

The birth of the long-awaited baby is preceded by nine months of tedious waiting. And to know the exact time of the birth of the baby, you need to set the current gestational age.

As a rule, the absence of menstruation is the first sign of pregnancy, forcing a woman to turn to all sorts of ways to clarify her condition. You can do this at home using a pharmacy test or by resorting to folk remedies using iodine or baking soda.

Moreover, today it is possible to determine pregnancy in the early stages - before the delay in menstruation. All methods will be discussed in more detail in this article.

Establishing the presence of pregnancy using folk methods

In a small portion of urine collected after waking up, add a couple of drops of iodine or a spoonful of soda. Assessing the result of the chemical interaction of substances, we can come to the following conclusions:

1. Youpregnant if the soda does not react with urine, but simply precipitates to the bottom of the dish.
2. You are pregnant if iodine remains on the surface of the urine without dissolving in it.

Directly opposite processes of interaction of these substances with urine (violent reaction with soda or dissolution of iodine) indicate the absence of pregnancy.

True, such methods are rather emergency methods of establishing the very fact of pregnancy, rather than its exact date. However, these methods are effective only in the early period (less than nine weeks), therefore, a positive result will tell you the approximate date (first trimester).

Method used by gynecologists

Not all methods offered by medicine guarantee an accurate result. For example, the ways in which gynecologists determine the duration of pregnancy are designed for a woman to contact a consultation earlier (before the end of the first trimester of pregnancy, that is, by the thirteenth week).

Specialists at the antenatal clinic use the traditional medical method.

Based on changes in the uterus, an experienced specialist can accurately indicate the period. The unit of account is the length of the uterus at the time of examination, which corresponds to the number of weeks of pregnancy. For example, a length of thirty centimeters would correspond to thirty weeks.

The problem is that from the third month it becomes more difficult to determine the gestational age by weeks in this way. Because up to a certain pointThe embryo develops in different women in the same way. At a later date, the development of the unborn child can occur individually, depending on the genetic characteristics of the mother's body, as well as the presence of certain diseases.

To more accurately determine the gestational age by weeks, a specialist gynecologist, using a tazomer or a centimeter tape, measures the height of the uterine fundus in relation to the woman's womb, as well as the circumference of the abdomen of the expectant mother. To avoid errors, measurements are taken with an empty bladder.

In the later period of gestation, the priority way to clarify the data on the period is to control the volume of the abdomen of a pregnant woman. In particular, a tazomer is used to determine the size of the fetus. The doctor sets the body parts of the baby by touch, and then takes measurements. In this case, one part of the device (tazomer) is located at the bottom of the head, the other - in the area of the fundus of the uterus, where the baby's bottom is usually felt.

It is believed that the value obtained as a result of such a measurement is equal to half the length of the baby. The value obtained during the measurement must be multiplied by two and subtracted about five centimeters. The gynecologist divides the final result of the calculation by five and thus determines the current gestational age in months.

The traditional method of determining the term is quite effective until the end of the first trimester of pregnancy, but at later dates it can have large errors. Therefore, along with medical methods, widelyother timing methods apply.

Obstetric method of calculating the gestational age

In addition to examining and determining the size of the uterus, the specialist starts from the date of the last menstruation. You can also determine the gestational age by menstruation yourself: by the first day when a woman's menstruation begins, you need to add 280 days (forty weeks).

Such a calculation is a rough definition of the term, since it is not based on the very moment of conception, but on an approximate period setting, based on the frequency of the patient's monthly cycle.

Intrauterine, the fetus develops fully within thirty-seven to forty-two weeks, depending on the individual characteristics of the course of pregnancy. Thus, the exact date may differ from obstetric. And the discrepancy period reaches about two weeks, since on average it is exactly two weeks that separate the moment of the beginning of the monthly cycle from the estimated moment of ovulation (the most favorable time for conception).

Determining the duration of pregnancy by menstruation is considered the most simple and affordable way. It is enough to know the date of the first day of the last menstruation. By counting the number of weeks that have elapsed from this date, you will determine your current due date yourself.

Negel formula calculation

A simple method to determine the due date for women who have a regular monthly cycle. The calculation is carried out from the date of the beginning of the menstrual cycle according to the following formula:

start date of last period- three months + seven days=due date.

Calculation of the term by the moment of fertilization of the egg

This method requires more precise information. In particular, in order to determine the gestational age by the date of conception, it is necessary to know the date of ovulation. This is the most favorable time for fertilization. If the pregnancy was previously planned and the woman specifically calculated the most favorable period for conception, it is easy to determine the exact date by adding the number of weeks that have passed since her moment of ovulation to the date of ovulation.

With a regular monthly cycle, it is not difficult to calculate the moment of conception. Using the average duration of a normal twenty-eight-day cycle, we set the approximate date of ovulation. It will fall approximately on the fourteenth day, that is, exactly in the middle of the cycle. For those who do not know how to determine the exact gestational age on their own, this method may well be suitable. But with a non-standard cycle length for a woman, this option is unlikely to give accurate values.

Research method

If it is not possible to set the period by the above methods, this can be done by ultrasound examination (ultrasound), which is carried out only by a specialist using special equipment. Many say that this is the only way to determine the exact gestational age. But even here there are nuances. The most accurate result of the study is possible only in the first thirteen weeks of pregnancy, when the development of the embryo in different women, asusually proceeds normally. However, a planned study is usually prescribed in the second trimester, so in the early stages you can do an ultrasound on your own for a fee. This is one of the most popular ways to determine your pregnancy.

During the procedure, the specialist determines the size of the fetal egg and the embryo itself. Based on the measurements obtained, the current gestational age is established. As a rule, the term set by the specialist coincides with the obstetric one (provided that the woman had a regular monthly cycle before pregnancy).

Fetal movement

The first signs of fetal movement are an alternative method of how to determine the gestational age. Can be used in the second trimester. The feeling of fetal movement during the normal course of pregnancy first occurs at the twentieth week of pregnancy (or at the fifth month). Multiparous mothers have earlier signs of movement, for example, at the eighteenth week.

This method cannot be considered reliable due to the fact that different women begin to feel their child at completely different stages of pregnancy: someone a little earlier than the generally accepted period, someone, on the contrary, later. In addition, some primiparous mothers often confuse the movements of the fetus with the processes occurring in the intestines.

Pregnancy test - how long does it determine?

This is the most popular way among modern women. Many expectant mothers are interested in the question of how long the pregnancy test determines herAvailability. Judging by the instructions of most of them, it is advisable to do it starting from the first day of the delay. In pharmacies today you can find electronic express tests, the manufacturers of which promise to indicate not only the fact of pregnancy, but also its duration. Their action is based on the level of hCG, and it does not always correspond to the required indicators.

Determination of the term in terms of hCG

Almost from the moment of conception, the mother's body begins to actively produce chorionic gonadotropin (hCG). The pregnancy hormone performs the function of protecting the embryo. Each week of pregnancy corresponds to the permissible level of the hormone, according to which it is possible not only to clarify the term, but also to identify deviations in the development of the fetus, as well as pathologies during pregnancy. Human chorionic gonadotropin is produced especially intensively in the early stages, and starting from the twelfth week of pregnancy, its level in the blood of a pregnant woman decreases. Maximum hCG values are observed two months after conception.

Experts note that this is not the most reliable way to determine the gestational age. The problem is that the hCG level obtained in the laboratory, depending on various factors, can have a fairly large scatter. The values of the hormone vary (may be reduced or too high compared to the norm) in the presence of pathologies, as well as in the presence of a multiple pregnancy in a woman.