How to correctly and accurately determine the duration of pregnancy?

Is it possible to determine the date of birth at home using calendars?

First, you need to find out what PDR is - a medical term that certainly appears in the exchange card of pregnant women on the day of registration at the antenatal clinic. This is a preliminary date of birth, and it is not for nothing that it is not called exact, because no one in the world can say with 100% certainty that you will give birth on a certain day of the month. But presumably you can calculate the date of birth of a child at home, knowing the gestational age. Online pregnancy calendars are a good help with calculations, telling expectant mothers significant events during the gestation period. They describe all the changes that occur in the mother and fetus depending on the stage of pregnancy. The calendar will remind you that the time has come for the necessary tests and therefore it is time to visit the doctor. Just don’t be surprised that the electronic assistant may be up or down with the date by 1-2 weeks.

Having learned about pregnancy, women begin to calculate when the baby will be born.

Based on my own experience, I will say that the reliability of such calculations is highly controversial. But it does a good job of helping you to distract yourself from anxious thoughts with the anticipation of meeting your child soon. You can fantasize about what the weather will be like outside on your baby’s birthday. I imagined snow, and in 2008 it really fell very early; the morning after my son was born, I looked out the window of the maternity hospital and saw a white blanket covering the ground. By lunchtime everything, of course, had melted, but since then I have associated the first snow with something joyful and long-awaited. And it doesn’t matter that this day did not coincide with the PDR in the exchange card.

The signals given by the body of the expectant mother most accurately indicate the impending birth.

Girl or boy?

While expecting a child, families wonder who will be born, a girl or a boy. Grandmothers are trying to determine this by certain signs. If the belly is cone forward: it means it will be a boy. If your belly is round and your hips are fuller, then you should be expecting a girl.

Now the sex of the child is determined by ultrasound. Ultrasound “sees” better than any grandmother: who is hiding in mom’s tummy.

READ ALSO: How to conceive twins and try to influence the gender of the babies. Natural and artificial ways

But in young families where they are expecting their first child, they want to know the sex of the child even before he gets into this belly. Families that already have children are also planning a baby. I have a boy, I want a girl. Or vice versa.

READING: How to conceive a girl: tables, calendars, methods and tips

READING: How to plan and conceive a boy: all known methods

Doctors believe that if sexual intercourse occurs on the eve of ovulation, a girl will be born. If after - a boy.

Eastern sages advise: in order to have a son, sleep with the head of the bed facing north. For those who are expecting a daughter - to the south.

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Pregnancy symptoms that indicate labor is coming soon

Pregnancy does not necessarily last exactly 266 days from conception or 280 from the first day of the last menstrual period before conception. Each person is individual; if one person needs 37 weeks to be fully ready for birth, another may stay in the mother’s womb for 41 weeks. As a rule, shortly before giving birth, pregnant women experience similar symptoms, signaling an imminent joyful event:

• the stomach drops. In first-time mothers, the previously protruding tummy noticeably shifts downward, because the baby’s head drops into the pelvis approximately 2-3 weeks before birth. Multiparous women notice a drooping of the abdomen almost before the birth itself;
• Braxton-Hicks training contractions appear. They feel like cramps during menstruation. Pressure increases on the pelvic organs and in the rectum. Pregnant women feel a nagging pain in the sacral area; in multiparous women, pain is also felt in the groin;
• weight gain stops. If a woman adheres to the principles of proper nutrition, in recent weeks she even loses up to 1–1.5 kilograms. This is called physiological weight loss and is associated with ridding the body of swelling;
• the woman's behavior changes. In recent weeks, the so-called nesting instinct, which consists in the desire to make your home more comfortable for the birth of a child, is especially pronounced. Mothers are starting to clean things up more often, and some have an irresistible desire to freshen up the renovation. At the same time, periods of excessive activity alternate with complete apathy, when the pregnant woman does not want to see anyone;
• change in vaginal discharge. Shortly before giving birth, expectant mothers notice that vaginal discharge has become thick and profuse, sometimes with bloody impurities due to burst capillaries when the uterus begins to dilate. But if blood is released profusely, you need to immediately contact an ambulance so that the woman in labor is accompanied by doctors on the way to the maternity hospital;
• discharge of the mucus plug. This can happen two weeks before birth and when contractions have already begun, which is considered normal. During pregnancy, the thick substance acts as a natural lock in the cervix, preventing the placenta from leaving along with the fetus. When the time comes to give birth, there is no need for traffic jams;
• precursor contractions that replace Braxton-Hicks contractions. The sensations become noticeably painful, the uterus contracts more and more often, but the cervix does not dilate yet;
• loose stool. Even with the same diet, diarrhea may begin - this is the body trying to get rid of everything unnecessary so that nothing interferes with the baby’s passage through the birth canal.

Video: harbingers of childbirth from a young mother

But all these signs relate to the last weeks, and we need to find out the date of birth, when the period is much shorter.

Pregnancy diagnostic system

If you do not rule out the fact of pregnancy, you need to visit a gynecologist and undergo a diagnostic ultrasound to rule out an ectopic pregnancy. It is impossible to detect an ectopic pregnancy with a conventional pregnancy test. Because, as in the case of a normal pregnancy, the test will show a positive result. But the only difference is that an ectopic can be life-threatening and require surgical intervention.

Pregnancy tests

In order to independently find out whether a woman is pregnant or not at the initial stage, with indirect signs and suspicions, you can purchase a pregnancy test. This is the fastest and easiest method. There are a huge variety of tests, from the simplest and cheapest to the most expensive and electrical. There are four generations of tests, namely:

• Regular paper strips;
• Cassette or tablet test;
• Jet test;
• Electronic, digital test.

How does a pregnancy test work?

A pregnancy test works like a litmus test. It determines the presence in the urine of a special hormone (human chorionic gonadotropin), which is secreted by the placenta. Each woman can produce different antibodies contained in a special hormone. Therefore, it is best to take a pregnancy test that contains all known antibodies; it will definitely show the correct result.

The test can become false positive if a tumor develops in the organs of the female reproductive system.

But false-negative tests are less common and can only mean that the level of the hCG hormone is still very low to diagnose pregnancy.

Methods for calculating due date

About 80% of pregnancies last 38 weeks, this makes it possible to determine PDR from the first days. It is important to understand that gestation periods are divided into 2 types:

• embryonic - from conception (266 days). You can accurately determine the gestational age if you know the date of conception;
• obstetric - from the first day of the last menstruation (280 days). Most often used by doctors to determine the expected date of birth.

Video: gestational age and due date

Estimated due date based on menstruation

The method is based on the menstrual cycle. There are several ways to calculate the monthly allowance:

• add 280 days to the first day of the last menstruation (LMP) before conception, you get LMP - estimated date of birth or approximate day of birth;
• use Naegele’s formula - PDR = PDPM - 3 months +7 days. You need to count back 3 months from the PDPM and add 7 days to the resulting date. This method is much simpler than adding days on a calendar;
• online calculators. The simplest and easiest way to find out the possible date of birth of your baby. These calculators are based on the same Naegele formula and are easy to find on the Internet.

For example, PDPM was on August 13, birth should be expected on April 20.

With the advent of online assistants for calculating PDA, expectant mothers no longer need to manually monitor calendar numbers, counting down 280 days before giving birth

Calculating the PDA by menstruation has a significant drawback - not all women have a menstrual cycle of 28 days, and the difference, up or down, affects the date of ovulation and leads to inaccuracies in calculating the expected date of birth. Therefore, it is more correct to count from ovulation.

Date of birth based on ovulation and conception

Every month, an egg matures in one of the ovaries (less often in two at once). Ovulation is the process of the release of a mature egg from the ovary and its movement towards the uterus through the fallopian tube, during which fertilization occurs with sperm entering the fallopian tube. If conception does not occur, the layer of endometrium lining the inside of the uterus is destroyed and, along with bloody discharge, comes out. This is called menstruation, which marks the beginning of a new monthly cycle, which will also include ovulation.

Conception is possible within two days of the egg moving through the fallopian tube, and sperm can wait up to 7 days for a chance of fertilization. Ovulation can be calculated by knowing your menstrual cycle. Most often, its duration is 28 days, but it can be 22 or 35, and even irregular due to the woman’s health. The pharmacy sells special tests for those planning a pregnancy, suggesting favorable days for conception. On average, it occurs 14 days after menstruation.

Ovulation strip tests are similar in principle to pregnancy tests, but instead of hCG they react to luteinizing hormone, the level of which in the blood and urine increases significantly before the release of the egg from the ovary.

If you are sure of the exact day of ovulation, add 266 days to it, and you will get your MDA. For example, ovulation occurred on March 10, childbirth will occur around December 1.

But, to be honest, those who became pregnant through in vitro fertilization (IVF) know the real date of conception, and they also experience discrepancies between the expected and actual date of birth.

Possible date of birth based on the first fetal movement

In recent years, more and more doctors are trying not to pay much attention to the day of the baby’s first movement when calculating the maximum age limit. This indicator serves rather as an auxiliary way to confirm a guess. With the first pregnancy, 20 weeks remain from the moment of the first movement until birth, and with a second pregnancy, 22 weeks remain. For example, the first movement was on July 27, the baby can be born on December 14 during the first pregnancy or on December 28 during subsequent ones. This method is ineffective for the following reasons:

• many mothers hear the first movements later or earlier than 20 weeks during the first pregnancy or 18 during subsequent ones. Women who are actively involved at work or in social life usually feel the baby's kicks later than those who have a lot of free time to listen to the condition of their baby;
• inexperienced mothers sometimes confuse their own intestinal peristalsis or gases inside themselves with the movements of the fetus. Overly impressionable people sin with this, even being pregnant not for the first time, convincing themselves and others.

If the baby is well and comfortable in the womb, and the mother does not experience any external or internal stimuli, then the movements are rhythmic and smooth

Date of birth upon first visit to the antenatal clinic

This method is called “by first appearance at the antenatal clinic.” An initial examination by a doctor in a gynecological chair determines the presence of pregnancy no earlier than 5 weeks from conception; by this time the uterus increases in size, rounds and becomes soft. Up to 12 weeks, it is possible to almost accurately determine the gestational age, which gives reason to assume when the baby should be born. The survey conducted when filling out the exchange card includes establishing the gestation period according to the menstrual cycle. For example, the doctor determined the presence of pregnancy in September, and the last menstruation was on July 15. In this case, the traffic deadline will be March 22. Prescribed tests for the level of human chorionic gonadotropin (hCG), the pregnancy hormone, help indirectly confirm the assumption. But the indicators in the adjacent weeks overlap each other, and it is useless to wait for the result up to a week in the period based on the hCG level.

At the first visit to register for pregnancy, the gynecologist examines the woman and enters the patient’s verbal answers into the exchange card

Therefore, the pregnant woman is sent for an ultrasound, where the most reliable data to date is obtained.

How to find out PDR based on ultrasound results

Ultrasound, or ultrasound examination in the first trimester helps to establish the actual duration of pregnancy with an error of 1-3 days, therefore the date of birth in preliminary detention is most often close to the real one. You can calculate it by adding 38 weeks (266 days) to the date of conception. For example, an ultrasound was done on January 14, the gestational age by that day was 9 weeks. This means that according to the obstetric period, 31 weeks need to be added to January 14, and according to the embryonic period - 29 weeks. Accordingly, the traffic agreement will be received on August 19 or 5. In the first trimester, all children in their mother's wombs have similar sizes at the same times. After 12–13 weeks of pregnancy, the fetus begins to develop according to heredity and it is almost impossible to establish PDD in the second and third trimester based on the size of the child.

In the second and third trimester, ultrasound helps monitor the development of the baby, but the period can realistically be set to a maximum of 14 weeks of pregnancy

Table: methods for calculating the expected date of birth and their effectiveness

Other methods for determining gestational age

For various reasons, many women experience disruptions in their menstrual cycle. In these cases, standard counting methods are not suitable, and you have to resort to other methods. Here is their list:

• In the examination chair at the gynecologist
• Ultrasound
• When you feel the baby's first movements
• Depending on the size of the uterus

In particularly uncertain cases, the doctor can use all of these methods to establish PDR.

Examination by a gynecologist

In the first trimester of pregnancy, a qualified specialist can determine the due date by touch. By assessing the boundaries of the uterine cavity, we can conclude that pregnancy has begun (4 weeks) if the uterus is the size of a chicken egg. An enlarged uterus, the size of a goose egg, indicates 8 weeks.

Ultrasound

Ultrasound examinations currently provide very accurate data on gestational age. The device allows you not only to see the fertilized egg, but also to measure its parameters. In the first 12 weeks, only the diameter of the egg is measured and compared with normal values. In subsequent trimesters, when the fetus becomes human-like, the circumference of its head, chest and abdomen is measured.

The most accurate age can be determined by ultrasound in the early stages, since the more the baby grows, the more strongly he expresses the genetic characteristics inherited from his parents: he may be larger or smaller than other children at the same stage of development.

Baby's first kicks

According to medical research, a pregnant woman will first feel the movements of her baby at 20 weeks of pregnancy. If she is expecting a baby for the second, third and further times, then the period of waiting for the first tremors is reduced to 18 weeks. Based on this, you can also calculate your term.

However, the accuracy of this technique is quite controversial. In fact, the tiny baby in the mother’s womb makes its first movements before the 12th week, but he is still so small that the mother does not feel it. Although there are exceptional cases.

Very often, young mothers who are pregnant for the first time mistake gas formation in the intestines for the baby’s movements. Especially if they have a tendency to flatulence. But still, as soon as you can confidently say that you felt the first tremors, be sure to inform the doctor who is managing your pregnancy.

The height of the uterus is equal to the week of pregnancy

Another very convenient way to clarify the date involves measuring the height of the uterus. It is carried out with a special meter - a pelvis meter. A pregnant woman cannot use it herself, so this procedure is performed by a doctor while she lies on the couch. The pelvis gauge measures the distance from the top to the bottom of the uterus.

The resulting value in centimeters indicates the current week of pregnancy, that is, the height of the uterus is 25 centimeters at 25 weeks.

The combination of all of these methods gives an accurate picture regarding the date of birth.

Calculation using online calculators, calendars and pregnancy tables

It is very convenient to calculate the expected date of birth using online calendars or calculators. Enter a phrase like “calculate traffic allowance using a calendar or online calculator” in the search bar, and you will be offered many links to sites that provide a similar service. You only need to fill out a few fields - about the duration of the menstrual cycle and the first day of the last menstruation before conception - and click the "calculate" button. There are calculators for calculating ovulation and with an expanded range of information provided. You can find out how old your baby is at the time of calculation, his estimated size, and even under what zodiac sign he may be born.

To find out your PDA, you need to find the day of your last menstruation in the line marked with an asterisk, and the expected date of birth will be right below it, in the pink line

You have come across MDR calculation tables more than once not only on the Internet, but also in magazines. Their use does not require the services of the World Wide Web or complex calculations. The pregnancy tables have 24 rows, grouped into two - top and bottom. It is enough to find the month of your last menstruation, select the date of its beginning in the top line and the date in the bottom line will be the same PDR.

Childbirth occurring from 37 to 42 weeks of pregnancy is not a pathology. No more than 5% of women give birth on the expected day.

There are many ways to find out the expected date of birth, but only one out of twenty babies is born on the predicted day +/- 2-3 days, 17 out of 20 are born with a difference of up to two weeks, more or less from the PDR. And 2 babies may be born significantly prematurely or a little later; doctors will not allow the pregnancy to last longer than 42 weeks.

Video: obstetrician-gynecologist about the date of birth

Dates of first and second births

The first pregnancy usually lasts slightly longer than subsequent ones. And there are natural physiological reasons for this. After a vaginal birth, the pelvic muscles become more flexible; tears and scars can make them weaker.

The cervix effaces faster in subsequent pregnancies, which is why labor begins at an earlier stage. The second pregnancy may be 7-10 days shorter than the first.

However, this statement should not be taken as a rule. Second and subsequent pregnancies may be longer than previous ones. There is no pathology in this. Comparing your feelings with your first pregnancy, the expectant mother should not worry. The due date will depend on the size of the fetus, its gender, and the state of health of the mother at the time of the second pregnancy.

If during the first birth a cesarean section was required, then the end date of the second pregnancy may not differ from the previous one. In this case, the birth canal does not have injuries or sprains.

General recommendations on how to calculate your due date

Experienced mothers are skeptical about calculating the due date, because they know that the baby will be born when its due date comes, and not as you calculated. But still, there are some recommendations for pregnant women on calculating the maximum permissible limit:

• When planning a pregnancy, keep a calendar of ovulation and menstrual cycle. This will not take much time, but it will greatly facilitate calculations when pregnancy occurs;
• Try to get an appointment with a gynecologist as soon as possible if you suspect pregnancy. Already at 5 weeks, the uterus changes, and in case of doubt, an ultrasound will come to the aid of the doctor;
• An ultrasound scan should be completed before 12 weeks, especially if you find it difficult to accurately name the approximate date of ovulation or the start of your last menstruation;
• When making your own calculations, be guided by the menstrual cycle or doctors’ conclusions about the gestational age. This will allow you to estimate the date of birth as accurately as possible;
• auxiliary methods for calculating PDR - only for doctors. You need to get tested for hCG and promptly inform the doctor managing the pregnancy about the first movement of the child.

Video: how the maximum allowance is calculated

It is important to understand that the result of calculating the date of birth, including spontaneous ones, is rarely correct. The difference depends on the following factors:

• women under 20 and after 30 years of age are more likely to miscarry or overstay their pregnancies, especially the first;
• the presence of bad habits provokes premature birth;
• unfavorable social or environmental conditions negatively affect pregnancy to term;
• Chronic or acute forms of diseases can affect pregnancy. For example, women with diabetes often go beyond their due date, and infections speed up the birth of the baby;
• there is a genetic predisposition to premature or delayed birth, inherited from mother to daughter;
• In case of multiple pregnancy, birth occurs prematurely by an average of 2 weeks.

These are the main reasons that it is not possible to accurately calculate the MRP, but there are also secondary ones. It should not be surprising that children are born on a different day than indicated on the exchange card.

I was diagnosed with cervical erosion at the age of 17; the probable cause was hormonal imbalance. Erosion, combined with disruption of the endocrine system, made my cycle irregular. Sometimes menstruation occurred at the beginning and end of the month, or there were 33–35 days between them. They refused to treat erosion with cauterization before giving birth, but it was precisely this that prevented me from getting pregnant. By the age of 26, I had already stopped paying attention to the regularity of my cycle, and then a surprise awaited me, which will turn 10 years old this November. Oh, the doctor and I had a lot of trouble setting the deadline. At first it was assumed that I would give birth on November 30, then the ultrasound added almost 3 more weeks to this day. Based on the movement of the fetus, it turned out that the son would be born on December 10, but he hurried to us on November 22. And he’s still in a hurry somewhere, the restless little boy. And his cousin, according to the obstetric date, should be born on July 7, and according to the ultrasound, a week earlier. That’s why my sister’s birthday is on July 4th. We wait. Although the doctor told her that the expected date of birth is more needed by obstetricians in order to prevent the woman from enduring the pregnancy. My son-in-law took a vacation, covering the end of June and the beginning of July, so that work would not distract him from his role as a new father. Among my friends, only one gave birth exactly on time, and that was because on that day she had a planned caesarean section according to indications. Still, it’s a good thing, this PDR, despite the errors, helps prepare for the arrival of a new family member.

Setting a deadline for an ultrasound examination

In fact, an ultrasound examination of fetal development and pregnancy is not intended to determine the duration of pregnancy. During such an examination, the diagnostician only indicates the period of fetal development, and whether it coincides with the period of pregnancy is already checked by the obstetrician-gynecologist with whom the woman is registered.

In the normal course of pregnancy, the period of fetal development and formation of the placenta according to ultrasound will coincide with the stated gestational age. And here it all depends on how the doctor determined your gestational age: using the formula for calculating the obstetric period or using a blood test for hCG.

If the discrepancy between the ultrasound data and the gestational age set by the doctor is significant, the doctor will either clarify the set date using the hCG test or prescribe additional tests to check the development of the fetus.