Methods for determining the gestational age and due date

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

Many women, having learned that they are in an interesting position, begin to dream of the day when the child is already born. An accurate determination of the timing of pregnancy and childbirth is possible only if the conception occurred in a test tube, that is, in the laboratory. However, doctors in all other cases still know how to determine the expected date of the birth of the child and they have their own methods.

Can everything be calculated exactly?

Determining the duration of pregnancy occurs most often on the basis of the results of ultrasound or on the basis of the exact date of the last critical days. Despite the fact that modern medicine has taken a step forward - only 4% of children are born on the predicted date, while 96% of babies appear a couple of weeks earlier or even a little later than the set day. Why is everything happening this way? Methods for determining the timing of pregnancy and the day of birth allow you to calculate the approximate date, while the gestational age can vary from thirty-seven to forty-two weeks, and all children born in this timeinterval are considered to be born on time.

Keep in mind that after determining the gestational age and the date of future births, it will be correct to assume that the birth of a baby can occur in a period that is counted two weeks before the due date and a week after it. Always remember this and don't worry.

How is the last menstrual period determined?

How does everything happen? During the initial visit to the obstetrician-gynecologist, he will ask when was the first day of your last menstruation. Then the doctor uses the Naegele formula to determine the gestational age for the last menstruation. What is this formula? For the calculation, the first day of the past critical days is taken, three months are subtracted from it and seven days are added to the received date. If the menstrual cycle is less than twenty-eight days, then the difference will need to be subtracted from the received date (for example, three days if the cycle lasts twenty-five days). If the cycle is longer by a couple of days, then the difference is added to the expected date of birth.

Is this method of determining the duration of pregnancy by menstruation accurate? The technique is used if a woman regularly keeps a calendar of her menstrual cycle and remembers exactly the start and end dates of menstruation. However, there are still problems, because in a normal state, pregnancy can last from thirty-eight to forty-two weeks, so there will be inaccuracy. It is also worth noting that the method works only when the expectant mother does not have problems with the cycle. Heshould be stable, uniform and last exactly 28 days. In such situations, the pregnancy will most likely last 280 days, or, in medical terms, ten obstetric months, starting from the first day of the last menstruation.

Determining pregnancy by ovulation

Determining the gestational age before ovulation delay is quite simple. With a cycle of 28 days, ovulation occurs around the 14th day. We add 38 weeks to this day and that's it. This will be the day of the expected birth. Is this method accurate? The fact is that for many women the cycle is unstable and has deviations up or down. The interval between periods can be 25 days, and can be 32-33 days. How to determine the day of ovulation? It occurs 14 days before the start of the next menstruation, but these calculations are not always accurate. All due to the fact that a mature egg lives for a couple of days, and spermatozoa are able to live inside the female body up to five days after intercourse. This method of determining the duration of pregnancy works best if the time interval between sexual intercourse was at least 6 weeks.

Ultrasound as a way to establish pregnancy

How is everything calculated? Based on many years of research and observation, special tables were compiled in which the gestational age is compared with the parameters of the fetus (the distance from the coccyx to the crown is taken). Head circumference is also taken into account.chest and even thigh length. Is it possible to determine pregnancy in the early stages? Of course, but in such cases, the size of the fetal egg is taken.

Is this method accurate? At the moment, this technique is considered the most accurate. The question arises: “At what stage of pregnancy is it allowed to use it to determine the date of birth?” Ultrasound is best used for a period of 4 to 13 weeks. During this period of time, the size of the fetus in women does not actually differ, therefore, it is possible to establish the gestational age even with an accuracy of up to a day. True, we should not forget that the later the measurements are taken, the greater the error will be. Keep in mind right away that in the second and third trimester, many factors affect the fetus: heredity, genetics, mother's nutrition, and so on. Therefore, the size of the children may vary, and the due date may not be set accurately.

Results of the examination to determine the gestational age

As soon as you appear at the doctor's for a checkup, the specialist will try to estimate the size of the pregnant uterus, and in particular the height of its bottom, in order to determine the gestational age. Is this method accurate? Experienced doctors are not magicians at all. The size of the uterus and the height of the bottom in most cases depend on the size of the child, the volume of amniotic fluid, the presence of pathologies, and so on. The shorter the gestational age, the easier it will be to take measurements and determine the date of the baby's birth.

How to determine the gestational age by the height of the uterine fundus?

Determining the duration of pregnancy is carried out withexamining the uterus. The height of the uterine fundus, or VDM for short, is the distance between the upper zone of the pubic articulation and the upper part of the uterine wall, which protrudes from the pelvic cavity. When the fetus begins to grow, the uterus will increase accordingly and, starting from the end of the 4th obstetric month or the 16th week, the fundus of the uterus can already be measured through the anterior abdominal wall. Before this period, the specialist sets the growth rate of the uterus only during a vaginal examination.

Measure the height of the fundus of the uterus will be at each visit to the doctor, starting from the 16th week. Before that, it is possible to estimate the gestational age by monthly or in any other way.

How is the measurement process? The woman lies down on the couch, straightens her legs, it is desirable that the bladder is empty. The doctor, as soon as the patient lies down, measures the height of the fundus of the uterus using a centimeter tape. The study will take no more than a minute, but it will allow you to judge the nature of the baby's growth, its position and the volume of amniotic fluid.

Of course, there are generally accepted values of WMD that correspond to each stage of pregnancy, but there are always many factors to take into account and the fact that this is an individual indicator that can vary within three centimeters.

Always, conducting such a kind of analysis to determine the gestational age, pay attention to how exactly the WMD increases compared to the previous indicator. From the 24th week of pregnancy, the WDM will coincide with the gestational age.

If WMD is below normal then it maytestify to the following factors:

• an error occurred in early pregnancy detection;
• the presence of a wide pelvis in large women;
• fetal growth retardation;
• reduced amniotic fluid volumes.

If the WMD is greater than normal, then this indicates the following:

• fruit is very large;
• multiple pregnancy;
• mother's pelvis is narrow;
• fetus not positioned correctly;
• amniotic fluid increased.

Also, to control the condition of the fetus, its growth and the volume of amniotic fluid, measurements of the abdominal circumference at the level of the navel are carried out. The presented indicator directly depends on the personal characteristics of the expectant mother, the thickness of subcutaneous fat, therefore, the dynamics of the increase in circumference is taken into account. These parameters allow you to determine the possible weight of the child. To do this, you need to multiply the number of VDM by coolant. For example, the WDM is 36 centimeters, and the coolant is 95 centimeters, then it turns out that the possible weight of the child will be approximately 3420 grams. If the WDM indicators do not correspond in time by three centimeters or more, then the doctor prescribes additional examinations. Ultrasound, doplerometry and cardiotocography are performed, and then, based on the results obtained, treatment is prescribed and the tactics of the upcoming birth are established.

Dependence of MDD on the timing of pregnancy.

Term in weeks	Signs
Four	A womb the size of a hen's egg
Eight	Uterus by volume with goose egg
Twelve	The uterus will already be the size of a fist, and its bottom will be at the upper edge of the womb
Sixteen	The bottom of the uterus is located in the middle of the distance between the navel and the womb, it is about six centimeters above the womb
Twenty	The uterus stretches the abdomen, the bottom is at a distance of twelve centimeters, fetal movements appear, a heartbeat is heard
Twenty-four	The bottom of the uterus is located at the level of the navel, which is about twenty-four centimeters above the womb.
Twenty eight	The bottom of the uterus is four centimeters above the navel, the distance above the womb has already increased to twenty-eight centimeters
Thirty-two	The bottom of the uterus is already in the middle position between the navel and the xiphoid process, the approximate distance to the womb is already thirty centimeters, the abdominal circumference at the level of the navel is eighty centimeters, the navel is flattened
Thirty-six	The bottom of the uterus is placed in the same position as the xiphoid process, the volume of the abdomen has already grown to ninety centimeters, the navel is flattened
Forty	The bottom of the uterus descends in the middle between the xiphoid process and the navel, already the distance to the womb is thirtytwo centimeters, the circumference of the abdomen is ninety-six centimeters, the navel is protruding

Set the gestational age by the date of the first movement

How is this method of determining the duration of pregnancy? It is believed that during the first bearing of a baby, a woman is able to feel the movement of the fetus at about the twentieth week. If a woman has a second pregnancy, then the date of the first movements may come earlier - around the eighteenth week. Remember this day and just add twenty or twenty-two weeks to it. This will be the approximate date of birth.

How accurate is this method for determining pregnancy, sex and due date? Some mothers claim that they were able to feel their child at the seventeenth or even fifteenth week. These may well be erroneous sensations (movements in this state can be easily confused with intestinal peristalsis), but this may be true. It should also be borne in mind that thin women with high sensitivity recognize the movement of a child before full ladies. The place of attachment of the placenta also influences a lot, if it is located on the front wall, then it will prevent the mother from feeling the movement of the child, while the fetus can be very active or, on the contrary, inactive. An error of a couple of weeks when setting the date of birth is not uncommon.

Are all methods accurate?

If you practice all methods of determining pregnancy in early pregnancy to set the date of delivery, then still prepare forsurprises. Approximately 40% (if not less) of children are born on time (at the fortieth week), the rest of the babies are not so “punctual”. The child may rush to be born, or, on the contrary, may linger in the mother's belly. Therefore, when the thirty-eighth week comes, the expectant mother should be ready to go to the hospital at any moment.

Are there folk methods for establishing pregnancy?

Folk methods for determining pregnancy in the early stages also allow women to learn about their situation. At the same time, of course, it does not matter whether you thought about having a child or whether you already gave up and did not hope that a miracle would happen.

Many years ago, the fair sex also tried to determine pregnancy in the early stages, and each nation had its own methods. Jewish women walked barefoot through the tall grass, and the remaining footprints "told" whether the girl was in an interesting position or not. The Egyptians gave women a special drink to drink, if they vomited, then the pregnancy was confirmed.

Now women are not much different from the beautiful ladies of antiquity, but technology has gone far ahead, and now it is easier and easier to establish a pregnancy. However, even now, many girls want to know the result faster, which is why they resort to folk methods. Our great-grandmothers used these methods, but no one today will answer for their authenticity.

• Vintage pregnancy test. The test didn't always look like it does now, but somethingthey tried to do the same on ordinary test strips. Urine remained the main component, and iodine was used to determine the interesting position. You can also use any container or paper. If iodine is dropped into a container with urine and a drop remains on the surface, then pregnancy is confirmed. If you soak a paper strip in urine and drop iodine on it, then when the color changes to blue, the result is negative, lilac or purple is positive.
• The color of urine plays a big role. In the early stages, the urine is said to be dark yellow in color and very concentrated. Rumor has it that such urine has a good effect on the growth of flowers, and if you water them in the garden and wait, you will see the result. They will become more magnificent and more beautiful - this is a sign of pregnancy, nothing will change - the result is negative.
• Pity the plants? You can boil urine in a metal bowl and, after boiling, place the product in a glass container. During pregnancy, you will see flakes that precipitate. The technique is very popular, many women tried to determine their pregnancy in such a non-standard way.

Should I trust folk methods?

The methods are very interesting, but they will never give a 100% result, unlike a modern pregnancy test. If you wish, of course, you can try one of the methods for establishing pregnancy on yourself to check its effectiveness or just for fun. This is a fascinating activity, but still use proven modern techniques to guarantee. If pregnancyconfirmed, then by all means consult a doctor.

Why should women understand that due dates will be approximate?

The thing is that a woman will psychologically tune in to a certain date of birth, and if there are no contractions at the specified time, she may develop severe stress. This will lead to panic, there will be fear for the baby, anxiety due to a delayed or premature pregnancy. Some women even attempted to induce childbirth, of course, without the participation of a doctor. This should never be done. Early hospitalization will not bring positive emotions to anyone, especially the expectant mother.

Therefore, all women who are going to have children should immediately remember - the date, which is determined by the doctor during the examination or according to ultrasound, is approximate (estimated). Deviations are possible in any direction for up to a couple of weeks.

Believe me, the baby better "knows" when he needs to be born, so in a normal pregnancy, just trust your body and don't worry about it, go with the flow and everything will be fine.

When determining the likely week during which labor will begin, you will be able to mentally and financially prepare for the trip to the hospital. After all, when the contractions begin, you will not be at all up to it. The expected date will allow you to collect all the necessary things for yourself and your unborn child, mentally prepare for childbirth, because this is a difficult and painful process for every woman.

The main thing is not to worry, childbirth that began earlier orthose who are a few days late are more likely to give birth at the right time.

Let go of worry

When you are preparing for childbirth, it will be almost impossible to avoid excitement. Therefore, you should not worry at least for the expected date of birth, trust your baby and let everything go on as usual. There will be so much stress in the last stages of pregnancy, you should not add something else to yourself and worry just like that. It is better to spend time usefully, study materials on raising children, prepare a room for the baby, prepare bags for leaving for the hospital. Do not postpone these matters until the last minute, otherwise you can forget something, not have time, and then worry about it, and the expectant mother does not need any extra stress.