Trimesters of pregnancy - how to count them by week, and what happens in each period? What do you need to know about the trimesters of pregnancy by week, how to behave in the first, second and third? How to count trimesters by week

Motherhood is a huge responsibility, so during the pregnancy process, mothers have a lot of questions. Every girl knows that the gestation period is conventionally divided into trimesters of pregnancy by week. This approach is very convenient for specialists and mothers themselves to navigate deadlines and take into account their condition. Each trimester of pregnancy has its own characteristics and symptoms, characteristic changes in the fetus, the condition of the pregnant woman, etc.

Newborn baby gets ready for bed after feeding

So, conception has occurred and now there are nine months ahead, full of emotions and experiences, pleasant anticipation, and sometimes fears. The entire period while pregnancy lasts is divided into a certain number of weeks and trimesters of pregnancy. At the same time, managing pregnancy by trimesters involves dividing them into a certain number of weeks.

Gynecologists calculate according to the obstetric method, and begin to count the gestation period from the moment of the last menstruation, from the first day of the cycle. The pregnancy calendar by trimester is usually based on the obstetric principle. If we talk about the actual occurrence of conception, then it occurs 2-3 weeks later, but the exact day when fertilization occurs usually remains unknown.

The process of pregnancy takes a certain period of time. Immediately after fertilization, the cell is sent to the uterine body, its route runs along the fallopian tube, and the implantation process takes about a week or a little less; in fact, the egg is attached to the uterine wall approximately 5-7 days after fertilization.

According to obstetric terms, the trimester schedule is 40 weeks, 280 days, 10 obstetric months, each of which consists of 28 days. There are three trimesters in total. Such a division is incredibly convenient for monitoring fetal development and the pregnant woman herself. To determine the PDP, the obstetric calculation method is also used, and in the future the gestation period and the preliminary date of delivery are clarified with the help of delivery.

So, we have already clarified how many trimesters there are in pregnancy - there are three of them. But how many weeks are there in a trimester? This issue requires more detailed consideration.

• The first trimester begins with the first obstetric week and lasts until the end of the 12th week of gestation. During this period, placental tissues are formed and all the systems and organs of the future baby are laid down.
• In the second trimester of pregnancy, which lasts from 13 to 27 weeks, active fetal growth and development occurs.
• The third stage typically begins at 28 weeks. This stage lasts until delivery, and can last up to 41-43 weeks until the baby is born. At this stage of gestation, the fetus is actively preparing for childbirth and life separately from the mother’s tummy. Also at this time, the baby’s internal organs mature.

How the trimesters of pregnancy are distributed by week in the table.

Tracking pregnancy trimesters week by week is very convenient for managing a pregnant woman, comparing the compliance of fetal development with accepted standards, etc.

Features of each period

When a mother finds two lines on a test, it is quite normal that she has a lot of questions, such as how to count trimesters of pregnancy or how these periods are divided into weeks, how much is a trimester of pregnancy, etc. It is very important for doctors to know exactly which week of pregnancy is in at the moment with the mother. This makes it easier to detect any deviations or inconsistencies in fetal development.

But there are many contradictions regarding the division of trimesters into weeks, so such a division is considered to be very conditional. The weeks of pregnancy at each stage are characterized by a different number, i.e., the duration of the trimesters is not the same by week. The different number of weeks is associated with the course of certain processes, for example, by the end of the first stage the final formation of the fetal organs is completed, in the second stage they are actively developing and the baby grows, and in the third all organs ripen, the baby is rapidly gaining weight and growing, preparing for a new life outside of my mother's belly.

First stage of gestation

There are 12 pregnant weeks in the first trimester of pregnancy. They begin to count from the moment of the last menstruation, although in fact, conception is considered accomplished only after the implantation of a fertilized egg, i.e., from approximately the third obstetric week. So, during this period the birth of a new life occurs. It is at this stage that the patient’s interesting position is discovered and the doctor can already determine the pregnancy by week.

During this period, the mother should take special care, because there is a high risk of pregnancy failure. The slightest overload or nervous stress can disrupt implantation, which will lead to incorrect or insufficient fixation of the fertilized egg. The most dangerous periods for miscarriage are considered to be 3-4 and 8-12 weeks: the 3-4 week period means implantation processes, and 8-12 weeks are dangerous for pregnancy as a period of large-scale hormonal changes.

In the first trimester of pregnancy, mothers are faced with conditions such as toxicosis, swelling of the mammary glands, excessive emotionality and sudden mood swings. The fetus develops quite quickly, because already at 4-5 weeks a tiny heart begins to beat. According to the table of pregnancy trimesters by week, the first stage of gestation ends at the twelfth week. Moreover, by this time the baby has:

1. The cerebral hemispheres and vertebral structures are laid and formed;
2. Endocrine structures are already beginning to actively function;
3. The baby’s gender has already been formed;
4. Tooth buds appear and tiny fingernails begin to grow;
5. The facial features are already being determined, the baby is beginning to move, but the mother is not yet able to feel his motor activity, because the fetus is still too small.

By month, the end of this stage occurs in the third or beginning of the fourth month of gestation. During this period, it is necessary to monitor the condition very meticulously. Sexual intimacy is not prohibited, because pregnancy is considered a physiological condition, and not a pathology. But delicate and gentle sexual relations are recommended; the partner should avoid sharp thrusts and deep penetrations. If spastic painful sensations in the uterus or spotting suddenly appear, then the mother should immediately contact the antenatal clinic. By the way, by the end of the first stage the girl should already be registered as an obstetrician in the housing complex.

Second

It is necessary to include a salad of greens and vegetables in your diet.

In the second trimester of pregnancy, which begins at the 13th week and ends at the 27th week, the mother experiences, perhaps, the happiest and calmest period of gestation. She finally managed to get pregnant, the signs of early toxicosis are already disappearing, the threat of miscarriage has disappeared, the tummy has not yet become noticeable, but is starting to grow little by little, and mommy is full of energy and enjoys life. Usually at this stage girls literally blossom, and gradually, as the baby grows, their gait begins to change.

The enlarged uterus begins to put pressure, displacing the remaining pelvic organs, against the background of which trips to the toilet become more frequent, heartburn may appear, constipation begins to bother you, etc. But such manifestations are typical for the second half of this stage of gestation. Each girl is recommended to keep a pregnancy schedule, noting unusual sensations and new manifestations of an interesting position.

Now you should not avoid sexual intimacy with your spouse, because all the threats are behind you, there is no toxicosis, so you can safely practice any poses, pampering your beloved man. This approach will only strengthen the marriage bond, and, therefore, bring the spouses closer, but only in the absence of any individual contraindications for the pregnant woman. This period marks the first movements of the baby, felt by the mother. The placenta, which formed during the first trimester of pregnancy, now performs the functions of protecting the baby and providing it with the necessary nutrition and oxygen. But still, you should not allow bad habits, since any harmful effect can affect the baby.

Additional factors

At this stage, it’s time to go to the dentist if you have problems with your teeth, as well as buy new clothes for your wardrobe and complete important issues at work. After all, very soon, in a matter of weeks, mommy will no longer have time for this.

• You will have to love shoes without heels, because the tummy is growing rapidly, and the center of gravity is changing.
• Also, during pregnancy, you will have to remove thongs and replace them with regular cotton panties.
• From about 20 weeks, you can wear a special bandage that will relieve stress from the back, prevent the appearance of pain in the lumbar region and eliminate the formation of stretch marks.
• Now the amount of discharge may increase slightly, but you just need to make sure that there are no unpleasant itchy symptoms, blood or unpleasant odor.
• Since toxicosis has already passed, mothers often develop an insatiable appetite. You need to indulge your desires, but only in moderation, especially in relation to sweets and cakes.
• The first perceptible movements may resemble light bubbles. But when the baby begins to move more clearly, you need to be more attentive to his movements. Excessively intense tremors may indicate oxygen deficiency.

If previously mommy was prohibited from exercising in the pool or gym, now the doctor will most likely allow such activities so that mommy can properly prepare her body for the last trimester and childbirth. Mommy now needs to walk outside more often and ventilate the apartment several times a day.

End of pregnancy

If you have not conceived for a long time, you should consult a gynecologist.

Dividing pregnancy into trimesters helps mothers navigate when unusual symptoms appear. Some things are considered normal for a specific period, while others are considered a dangerous sign, so mommy will be able to understand in time that not everything is okay with the pregnancy. The third trimester begins at 28-29 weeks, and its logical conclusion will be childbirth. Doctors can calculate the preliminary day of birth as much as they like, but the child will be born only when he is completely ready for it. Sometimes birth occurs even at 44 weeks.

Usually, the mother has been on maternity leave since the thirtieth week, or even earlier, since the long-awaited birth is inexorably approaching. Most often, delivery is scheduled for the fortieth week, however, not everyone gives birth on time, especially with multiple gestations. In fact, any diagnosis will show that the baby at the third stage of gestation from 36 weeks is already viable and will be able to live outside the mother’s womb. But if the birth occurred before the 36th week, then special medical equipment is needed to deliver the baby.

In fact, each trimester is equal to quarters of the year, i.e., three months. During the last, third quarter, the baby gains final height, which can be about 49-52 cm. And its weight reaches about 3.5 kg. These parameters are approximate and are determined by genetic factors, lifestyle and diet in the last trimester before childbirth. It’s just that the main weight gain occurs in the last 3 months, so it is important to maintain moderation in food during this period and choose the right foods.

What else do you need to know

Now doctors strongly recommend not to overeat and exclude sweets and desserts from your diet. Try to introduce more movements into your life, although now they are somewhat more difficult than usual. At least walk more and wear a prenatal bandage. The baby can already hear his mother perfectly well and can be scared by excessively loud sounds, so try to talk to him in a soft voice, and turn on the music quietly, preferably something from the classics.

• Training contractive contractions of the uterine walls are considered quite normal, helping the uterus to adjust and prepare for labor.
• They are often confused with true contractions, but the latter are more intense and appear more and more often.
• An imminent birth is indicated by a characteristic prolapse of the abdomen, in which the baby moves down, its head descends into the pelvic region and rests on the uterine fundus.
• Also a sign of imminent delivery is the departure of the cervical mucous plug, which protects the entrance to the uterine cavity throughout pregnancy.

Now the main thing for mommy is to ensure a calm life, devoid of violent experiences and stressful situations. Sometimes this period is complicated by some unpleasant conditions that are revealed by timely diagnosis. These include the development of hemorrhoids, varicose veins, gestosis, etc. Therefore, it is important to undergo tests prescribed by your doctor.

Analysis by trimester

To identify possible deviations and exclude pregnancy pathologies, the mother periodically undergoes a number of studies and procedures during pregnancy. Blood tests determine the content of hCG, which begins to increase after implantation of the fertilized egg, and if the increase occurs slightly, this may indicate ectopic implantation of the embryo. Blood is also donated for various infections such as AIDS, hepatitis, syphilis, and the Rhesus of the mother and father is assessed. Diagnostics also includes studies for pathologies and antibodies such as toxoplasmosis, rubella, herpes virus or cytomegalovirus, etc.

When registering for obstetrics in a residential complex, you will need a medical examination by specialists such as a dentist, ophthalmologist, therapist, ENT specialist, etc. The first ultrasound examination is carried out at 10-12 weeks, and the second at 20-24. In the second study, you can already see the gender of the baby if he does not turn away and close himself from the sensor.

In the second trimester, the patient should be tested for TORCH infections. If previously a woman was no longer pregnant, had miscarriages or miscarriages, now they can prescribe triple testing for AFP, hCG and chorion. Thanks to this procedure, it is possible to promptly detect such pathological features in the fetus as the presence of Down syndrome, etc. At the last stage of pregnancy, ultrasound is usually prescribed at 30-34 weeks. Experts evaluate the baby’s readiness for birth, presentation, date of birth, blood flow between the uterus and placenta, as well as fetoplacental circulation.

So, we told you what trimesters are and what they represent. Each of these periods is characterized by its own characteristics. The main thing is that the girl needs to be as careful as possible during dangerous periods, when there is a threat of pregnancy failure, and undergo all tests and ultrasounds on time in order to prevent dangerous deviations and eliminate unfavorable factors.

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Almost every expectant mother has heard that the entire period of pregnancy is conventionally divided into trimesters. This makes it much more convenient for both doctors and pregnant women to navigate, because each of these periods has distinctive features. However, not every woman knows how the trimesters of pregnancy are divided into weeks.

First of all, it should be noted that there are several options for distributing all weeks of the obstetric calendar of pregnancy into three trimesters.

Some experts believe that the first trimester ends at 12 weeks, others at 13. There is also disagreement about the timing of the end of the second trimester and the onset of the third.

Nevertheless, the most rational point of view is when all 40 obstetric weeks of pregnancy are divided into three equal parts.

If we round the result to the nearest whole week, we get the following trimester boundaries:

• trimester – from 1 to 13 weeks inclusive;
• trimester – from 14 to 27 weeks inclusive;
• trimester - from 28 weeks until the baby is born.

This division of pregnancy trimesters by week is the most convenient.

Pregnancy calculator

Brief description of trimesters

Knowing how many trimesters there are in pregnancy and what to pay attention to during each of these periods, a woman can use her time more rationally and avoid many complications when carrying a baby.

First trimester

The first trimester marks the birth of a new life. This period begins from the first day of the last menstruation. Actually, at this moment there is no pregnancy yet, the female body is just preparing for a possible upcoming fertilization.

After conception, the cells of the embryo begin to divide exponentially.

It is at this time, when the expectant mother may not even be aware of the birth of a new life, that some kind of failure may occur in the programmed process of cell division, as a result of which a miscarriage may occur, or the unborn child may develop some congenital pathologies.

Fortunately, this happens quite rarely, so if the pregnancy progresses well, the embryo develops very intensively.

Second trimester

During the first trimester, a woman’s physiological state changes dramatically. Despite the fact that a pregnant woman’s figure undergoes almost no changes, a real hormonal storm occurs in her body, as a result of which symptoms of toxicosis often arise. The entire metabolism is rebuilt in such a way as to meet the needs of the unborn baby for the necessary nutrients. Immunity during this period decreases somewhat to prevent rejection of the embryo by the mother's body.

The most important feature of the first trimester of pregnancy is the formation of all systems and organs of the fetus. That is why a woman is contraindicated from taking almost all medications, smoking, drinking alcoholic beverages and indulging in other bad habits. It is necessary to lead a healthy lifestyle in order to prevent the development of pathologies in the unborn baby.

The second trimester is the calmest and most prosperous period for the expectant mother. All organs of the fetus are already formed, so you can worry less about the appearance of possible disturbances in the development of the baby. The baby in the tummy begins to take on a human form, but now it only vaguely resembles a newborn.

All functions of providing the fetus with useful substances are now performed by the placenta, which is a kind of barrier between the body of the mother and the child. But this does not mean that a woman is allowed to indulge her bad habits, because any negative impact in one way or another affects the unborn baby.

The woman's tummy is noticeably rounded. The expectant mother usually feels great during the second trimester of pregnancy, because her body is already accustomed to the new state. During this time, you can visit the dentist and other specialists, complete important tasks at work and update your wardrobe. In general, in this short period it is necessary to do everything that is planned for the next few months, without waiting for the final trimester of pregnancy.

Third trimester

The third trimester is the final stage of bearing a baby. The figure of the expectant mother changes radically, because the tummy reaches its maximum size. Nowadays it is difficult for a woman to do physical work, so it is necessary to enlist the support of family and friends.

The baby is rapidly gaining weight, taking up almost all the free space in the stomach. In case of premature birth, the child will have a better chance of survival the later he is born. All organs of the fetus are improved. The lungs prepare for the independent process of breathing, the endocrine glands produce hormones, the digestive system activates its activity, and the brain increases significantly in size.

In the third trimester, the expectant mother may experience some pregnancy complications: late gestosis, hemorrhoids, varicose veins and other ailments. That is why it is necessary to undergo the prescribed examinations on time and pay sufficient attention to yourself, not forgetting about rest and quiet time.

Tests during pregnancy by trimester

Throughout the entire period of pregnancy, a woman will need to undergo a number of tests and undergo quite a lot of examinations. The main ones are tests during registration, as well as screenings, one in each trimester.

The first trimester involves the following examinations:

• general blood analysis;
• a blood or urine test for hCG (human chorionic gonadotropin) during registration to confirm the fact of pregnancy;
• general urine analysis;
• blood chemistry;
• vaginal smear to detect bacterial infections;
• blood test to detect certain infections (hepatitis, HIV, rubella, etc.);
• blood test to determine Rh antibodies if there is a risk of developing Rh conflict.

First trimester screening is a comprehensive examination, which is carried out at 11-13 weeks, and consists of determining the level of certain substances in the blood: hCG, as well as PAPP-A, i.e. plasma protein-A associated with pregnancy. In addition, the screening examination includes an ultrasound scan of the fetus. Based on the screening results, the risk of genetic abnormalities in the fetus is identified. If the likelihood of anomalies is too high, the woman is recommended to undergo additional examination by a geneticist.

The second trimester is the time for the following tests and procedures:

• regular blood and urine tests;
• blood chemistry;
• measuring a woman’s body weight, abdominal circumference, fundal height of the uterus and other indicators;
• second trimester screening.

This comprehensive examination consists of performing a blood test at 16-20 weeks to determine the content of certain hormones, as well as conducting an ultrasound of the fetus. The level of free estriol in the blood is determined, as well as AFP (alpha fetoprotein), and the level of hCG is re-determined. During an ultrasound, a specialist measures the fetal body parameters and compares them with standard indicators located in special tables. Based on the results obtained, the risk of certain genetic abnormalities in the fetus is again calculated. In addition, during the examination, some complications of pregnancy can be detected, in which case it will be necessary to undergo the prescribed course of treatment.

The third trimester is the final one, so examinations are aimed at determining the condition of the fetus and identifying possible complications in the later stages. The examination package includes:

• repeated blood test to determine antibodies, some dangerous infectious diseases (hepatitis, HIV, etc.);
• urine analysis is performed several times to detect possible signs of gestosis;
• vaginal smear;
• screening of the third trimester, which consists of performing another ultrasound of the fetus. During the examination, the specialist determines the size of the child, pays attention to the degree of development of its organs, clarifies the presentation of the fetus, and assesses the condition of the umbilical cord and placenta.

Women with chronic diseases of the kidneys, ENT organs, liver, heart and other organs are prescribed additional examinations by appropriate specialists.

Each trimester of pregnancy is beautiful and wonderful in its own way. At first, the woman rejoices at the birth of a new life and tries to adapt to her new state. The middle of pregnancy is a calm and measured period when the expectant mother feels much better than in the first weeks of bearing a child. Finally, the final three months are notable for the fact that the long-awaited wonderful event of the birth of a baby will happen very soon, and this gives strength and confidence to the expectant mother.

It is common knowledge that a woman carries a child for 9 months, or approximately 280 days. In obstetric practice, it is customary to divide pregnancy into trimesters. How many trimesters are there in pregnancy? There are three of them in total, and in each trimester the expectant mother and her baby face pleasant changes and serious dangers. For the convenience of monitoring a pregnant woman, doctors use a pregnancy calendar by trimester, and trimesters of pregnancy are scheduled by week.

First trimester of pregnancy: 1-12 weeks

In the first trimester of pregnancy, the so-called symptoms of pregnancy appear: the absence of regular menstruation, early toxicosis, etc. It is during this period that all the vital systems of the child are formed, which is why it is so important to know how long the first trimester of pregnancy lasts, what dangers await mother and baby. Let's look at the first trimester of pregnancy week by week.

Your baby is growing:

• 1-2 weeks – the egg develops in the expectant mother’s body, approximately at the end of the second week ovulation and fertilization occur;
• 3 weeks – the fertilized egg reaches the uterus and is fixed in the endometrial layer;
• 4-5 weeks – the neural tube (the future central nervous system) is formed, the heart begins to beat;
• 6-7 weeks – the spine and hemispheres of the brain begin to form, the rudiments of the eyes, ears, arms and legs, liver, stomach, pancreas and thyroid glands appear;
• 8-9 weeks - all facial features are already distinguishable, genitals and intestines are formed, fingers appear on the hands;
• 10-12 weeks - the baby begins to move, marigolds appear on the fingers, and the beginnings of teeth appear in the gums. The heart is fully formed, and the endocrine system begins to produce hormones.

You change: Around the 6th week of pregnancy, signs of toxicosis appear: morning sickness and vomiting. The breasts swell and become sensitive, you visit the toilet more and more often - the growing uterus puts pressure on the bladder. You get tired quickly, sleep a lot, often get irritated and cry. This is normal - your body is being rebuilt “in a pregnant way.”

Important! Doctors consider the first trimester to be the most dangerous for the baby: any malfunction, infection, lack of vitamins or hormone imbalance in the mother’s body can lead to miscarriage. Critical for the child are 3-4 weeks of pregnancy (when the fertilized egg is implanted into the uterus) and 8-12 weeks (during this period the “hormonal storm” in a pregnant woman is especially strong).

Second trimester of pregnancy: 13-27 weeks

This time is considered the easiest and most pleasant period of pregnancy: toxicosis has subsided, the tummy is just beginning to grow, the tearful mood of the first weeks has been replaced by joyful anticipation, you want to do a thousand things. It is in the second trimester that women truly blossom.

Your baby is growing and very quickly! If at the beginning of the second trimester his height is approximately 10 cm and his weight is 30 g, then by the end of this period (27 weeks) the child weighs on average about 1.2 kg with a height of 35 cm! In addition, you can already determine the sex of the baby. The skeleton is fully formed, the muscular system and brain are developing. The baby moves a lot, and at 18-22 weeks the mother can already feel the first movements.

You change: your belly becomes more and more noticeable. Now is the time to get a “pregnancy” wardrobe, and your doctor will recommend wearing a bandage (from 20-22 weeks). The only thing that can overshadow this wonderful period is pain in the back or hip joints.

Important! At this stage, genetic abnormalities and severe fetal malformations can be identified, so if you are at risk, be sure to undergo the “triple test”.

Third trimester of pregnancy: 28-40 weeks

This is the last trimester of pregnancy, the most difficult for the expectant mother: the weight and proportions of the body have changed so much that it is already difficult to walk, sleep and even breathe. In addition, the woman is overcome by fears, she again becomes emotional and irritable.

Your baby is growing: all his organs are formed. The child can already hear, make breathing movements, and distinguish taste. The head is covered with hairs, and the body is covered with lubricant, which will help pass through the birth canal.

You change: The uterus continues to grow, and it is already difficult for you to breathe. False contractions may appear - the uterus begins to prepare for childbirth. You get tired quickly again, often run to the toilet, and don’t sleep well.

Important! At 28-32 weeks of pregnancy, signs of late toxicosis may appear: swelling, increased blood pressure, rapid weight gain, protein in the urine.

The most important, happiest period in a woman’s life, lasting 40 weeks or 9 months, is pregnancy. Throughout this entire period, the woman and her unborn baby will have to go through a difficult path before meeting each other. This time is usually divided into three periods, which gynecologists call trimesters, each of them has its own characteristics.

First trimester: 1-12 weeks

An important and difficult period during which the formation of all systems and organs of the fetus occurs, as well as the formation of the placenta, which will supply it with all nutrients and oxygen from the mother. At this stage of pregnancy, the female body faces difficulties (toxicosis, weakness, fatigue) and gets used to its new state. The first trimester is a dangerous period; it is during this time that 70% of all miscarriages occur.

Fetal development

In the first days of development (embryogenesis), the embryo is usually called a morula. It is similar in shape and size to a raspberry. On the tenth day, it reaches the uterine cavity and attempts to penetrate the mucous membrane, but it manages to achieve what it started only on the 24th day. At this point, there are more than 200 cells. After implantation of the embryo into the uterine mucosa, the process of life support for the embryo begins.

In the second month of intrauterine life, the embryo develops a heart. The fruit grows and develops rapidly and weighs about 4 grams.

At 5 weeks of pregnancy, the fetus's heart is already beating. At 8 weeks he makes his first attempts to move his limbs. By the end of the trimester, the baby will already have formed a cardiovascular system, gastrointestinal tract, spine, and face. Its weight is approximately 20 grams and its height is 10 cm.

Condition and feelings of a woman

In the early stages of pregnancy, the expectant mother may experience:

• cessation of menstruation;
• engorgement of the mammary glands;
• toxicosis (nausea, vomiting);
• decreased (increased) appetite;
• fast fatiguability;
• constipation;
• tearfulness, mood swings;
• increased urination.

The female body begins to get used to the new regime, the endocrine system is rebuilt, the lungs, heart and kidneys are preparing to work for wear, and the blood volume gradually increases.

In the early stages of pregnancy, nausea and vomiting occur in most expectant mothers. For some, the feeling of lightheadedness lasts throughout the day. The psycho-emotional state of a woman is subject to sudden changes in mood, spontaneous touchiness or irritability. The expectant mother feels constant drowsiness, absent-mindedness, forgetfulness and infrequent dizziness.

During this period, it is extremely important to start taking a complex of vitamins (Elevit, Vitrum, Femibion), as well as folic acid and iodomarin preparations. But they should be taken only after consulting a doctor.

A woman’s body begins to produce the hormone hCG (human chorionic gonadotropin), which is one of the main indicators of successful fertilization. It is now possible to determine pregnancy. To do this, you can donate blood to determine the level of hCG ( at 1-2 weeks it is 25-156 mU/ml, at 3-4 weeks - 1110-31500 mU/ml) or buy a special quick test at a pharmacy.

In the first trimester, a woman has a lot of responsibility. After all, the normal development of the fetus and, subsequently, the birth of a healthy child depend on her lifestyle, diet and nutrition during pregnancy. A woman needs to visit a gynecologist to register for pregnancy and childbirth.

Often in the first trimester a woman faces complications:

• threat of spontaneous abortion;
• low location of the placenta;
• non-developing pregnancy;
• ectopic pregnancy;
• hydatidiform mole.

Second trimester: 13-27 weeks

At this stage, changes continue to occur in the female body. The abdomen increases in size, which becomes noticeable to others. A woman feels cramped in her usual clothes, so she should think about purchasing comfortable things that will not hinder her movements. Most expectant mothers experience relief from toxicosis, increased fatigue, well-being, and vigor and activity.

By the end of the second trimester, the uterus noticeably increases in size. A pregnant woman feels heaviness in the stomach, a constant feeling of heartburn, and cramps in the legs.

During this period, the fetus is actively growing and developing, its organs and systems are fully formed. The placenta will also be fully formed, protecting the fetus from harmful external influences and ensuring the supply of oxygen.

The most common complications in the second trimester can be:

• premature birth or late spontaneous abortion;
• isthmic-ecclesiastical insufficiency;
• placental insufficiency;
• intrauterine infection of the fetus;
• gestosis (edema);
• iron deficiency anemia in a pregnant woman;
• haemorrhoids;
• gestational pyelonephritis.

If there are risk factors, the doctor prescribes prevention and treatment. The main thing is to identify problems in a timely manner.

Fetal development

The fetus grows quickly and gains weight. At the beginning of the second trimester, its weight is about 140 grams, and its height reaches 15 cm. Its size still allows it to actively swim in the amniotic fluid, move its arms and legs.

In the middle of the second trimester, a woman may feel her baby's faint kicks for the first time. The bond between the fetus and the mother becomes stronger. He is already able to sense the physical and mental state of his mother. The pace, rhythm and strength of fetal movement depend on these sensations. Therefore, a woman should worry less and think only about good things.

In the second trimester, the fetus's urinary system begins to function. He makes the first respiratory movements, and the lung tissue begins to produce a substance called sufractant, which is responsible for the production and absorption of oxygen. The digestive tract also begins to work. It swallows amniotic fluid, from which nutrients are absorbed in the small intestine, and the rest is sent to the large intestine and remains there, forming meconium (original feces). During the day, the baby is able to swallow up to 500 ml of amniotic fluid. Such exercises help develop his digestive system.

A vernix lubrication forms on the skin of the fetus, protecting it from constant exposure to amniotic fluid. And fat accumulates under the skin, allowing it to remain warm. Fine hairs appear on the scalp and eyebrows and lanugo (vellus hairs) appear throughout the body.

At this time, during an ultrasound, it is already possible to determine the sex of the child.

By the end of the second trimester of pregnancy, all organs and systems of the fetus are already fully formed. For the remaining period they will continue to actively grow and develop. The baby already weighs 700-900 grams and has grown to 35 cm. Weight and height depend on genetics and the course of pregnancy.

Third trimester: 28-40 weeks

This is the final stage of pregnancy. During this period, the female body begins to more actively prepare for the upcoming birth of a child. A pregnant woman has an increased risk of developing complications (hemorrhoids, varicose veins, heartburn). The fetus becomes large and can no longer move freely in the womb, which is why the nature of its movements changes. Now the expectant mother feels only tremors with her arms and legs.

Fetal development

At this stage, the fetus undergoes improvement of all systems and organs. Convolutions in the brain enlarge. His sense organs begin to function - he sees, hears sounds, tastes. Enough fat has already accumulated under the skin, the folds are straightened out, the body becomes proportional, and nails have grown on the fingers.

The fetus has already developed breathing, sucking, and swallowing reflexes. His entire body is still covered with lubricant, which will begin to decrease towards the end of the third trimester. The amount of vellus hair (lanugo) decreases, and by the end of the period it will disappear altogether. The cartilages of the ears and nose become elastic.

In the eighth month, boys experience descent of the testicles into the scrotum. In girls, the labia majora cover the labia minora.

At 37-40 weeks, the maturation processes of the fetus are completed, and it is completely ready for life outside the mother’s body. By this time, it takes its final position in the uterus and prepares for childbirth.

By the end of the third trimester, the weight of the fetus is on average 3500 grams, height - 55 cm.

Condition and sensations of the pregnant woman

During this period, the female body experiences increased stress due to the large size of the fetus. The uterus begins to put pressure on neighboring organs - it becomes difficult for the woman to take a deep breath, she is bothered by frequent urination, and venous outflow from the legs becomes difficult, which leads to swelling and heaviness. Because of the large belly, it becomes difficult for the expectant mother to move, and her back and pelvic bones begin to ache.

The load on a pregnant woman’s kidneys increases, because the fetus gains weight every day. From 31-33 weeks, training contractions (Braxton-Hicks contractions) become common. This is how the body prepares for the upcoming birth.

In the eighth month, a woman’s body releases relaxin, a hormone that makes the pelvic ring more extensible.

In the third trimester, a working expectant mother goes on maternity leave. Now she has a lot of time to buy a dowry for the baby, arrange a place and pack a bag for the maternity hospital.

Problems that the expectant mother may face:

• gestosis (late toxicosis);
• placental insufficiency;
• dyspnea;
• insomnia;
• constipation;
• phlebeurysm;
• haemorrhoids.

Each trimester of pregnancy is wonderful in its own way, although they bring some difficulties for the expectant mother. But no matter what difficulties she faces, there will always be positive moments. After all, it is interesting to watch how the baby grows, the body changes, new sensations arise, and the first movements appear. And when a long-awaited baby is born, all the difficulties of pregnancy and childbirth are overshadowed by this background.

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Carrying a baby is a special time in the life of a woman who is waiting for a miracle. It is very important to navigate the periods of pregnancy in order to know how the baby develops week by week and month, what is the time frame for the formation of its internal organs. Each stage of a child’s growth takes place within a limited time period—the sequence of all processes is rarely disrupted.

What is pregnancy

In the reproductive organs of a woman preparing to become a mother, the future baby grows and develops. First the embryo is called an embryo, then a fetus. The baby receives nutrition through the umbilical cord - a tube with veins and arteries that connects it to the placenta, a vascular sac. From the mother, the fetus receives blood saturated with oxygen and nutrients, and back - with carbon dioxide and metabolic products.

How does it arise

Pregnancy occurs after successful conception. This process is possible during the period of ovulation, when a woman’s egg (oocyte) matures in one of the ovaries and begins its journey to the uterus. Sperm in a man's seminal fluid, entering a woman's vagina during sexual intercourse, strive to reach the egg. Male cells “loose” the surface of the oocyte, and the sperm, the first to reach the inner membrane, merges - fertilization of the egg occurs.

There is an opinion that if two sperm penetrate the oocyte, a multiple pregnancy will occur, but such an embryo is doomed to death. A fertilized egg into which only one sperm has implanted turns into a zygote. The future embryo does not stop, but continues to move down the fallopian tube in order to attach to the wall of the uterus, after which pregnancy occurs.

How long does it last

If the countdown starts from the moment of conception, the intrauterine life of the fetus will be 38 weeks. However, the pregnancy period is usually counted starting from the first day of the last menstruation. Then the pregnancy lasts 40 weeks or 10 obstetric months. This practice of counting is a consequence of the fact that it is not always possible to accurately determine the day of conception.

Progression of pregnancy by week

Each stage of bearing a child has its own characteristic features that a woman should know about. Obstetricians divide pregnancy into trimesters of equal length. In addition, there is a practice of dividing pregnancy into periods determined by one or another stage of fetal maturation: these are the pre-implantation, implantation periods, organogenesis and the fetal stage.

Pre-implantation period

From the moment of conception and the actual onset of the first stage of pregnancy, 6-7 days pass. The zygote, in which cell fragmentation occurs, moves along the fallopian tube. At this point, the embryo is a ball consisting of 200 cells, which is called a blastocyst. Having reached the uterus, the blastocyst is fixed on one of its walls. This period is called pre-implantation.

Implantation period

The inner surface of the uterus is covered with a special tissue - the endometrium, which thickens during implantation. Blastocyst cells are attached to the endometrium by special processes. At this moment, the future placenta secretes a special hormone - human chorionic gonadotropin, which, entering the ovaries, prevents the onset of menstruation. The presence of this substance in the body helps determine pregnancy using a test.

Organogenesis and placentation

After successful implantation of the fertilized egg, the embryo enters a process of organ formation called organogenesis. The so-called axial complex is formed: neural tube, notochord, intestine. In parallel with the formation of organs, tissues are formed - nervous, epithelial, connective, and muscle. The latter serves as the basis for the heart, kidneys, genitals, and blood. Organogenesis is completed by the end of the fourth month.

In parallel with these processes, from the end of the second month, the formation of the placenta occurs. Until this moment, the chorion is determined in the embryo, which serves as the outer shell. With the development of the fertilized egg, villi appear in the chorion, which are gradually penetrated by vessels. Next, the chorion fuses with endometrial cells, and at 12-14 weeks the placenta forms in the uterine cavity.

Fetal period

From the 12th week until birth, the embryo is no longer considered an embryo, it is called a fetus. Obstetricians talk about the fetal or fetal period, in which, if there is a threat of miscarriage, they try to save the fetus. There are other critical periods of pregnancy, but the first danger is already over. By this time, the baby has already formed all the main organs and systems, he is growing rapidly, gaining weight and acquiring human characteristics.

Child development

The baby in the womb develops according to schedule. Each trimester, week, is characterized by new achievements of the baby:

Trimester/weeks	Period name	Development
1 (1-12)	Embryonic	The size of the fertilized egg increases from microscopic to 50-60 mm. The heart, brain and other organs are formed. At week 9, an ultrasound can already determine the sex of the baby. The first motor reflexes appear.
2 (13-27)	Fetal (fetal)	From 16-20 weeks, the first fetal movements are possible. By the end of the trimester, the baby’s length can reach 35 cm, and its weight can be about a kilogram.
3 (28-40)		The baby is actively gaining weight, and subcutaneous fatty tissue is forming. He moves less often because there is no longer enough space in the uterus for activity. Before birth, the baby's height approaches 50 cm and weight approaches 3-4 kg.

Feelings during pregnancy by week

A pregnant woman should understand what is happening to her body and how the child develops week by week in order to better interpret her feelings. Carrying a child is not only a gradual growth of the abdomen, but also a lot of other manifestations. During conception, until the embryo is attached to the wall of the uterus, the woman does not have any sensations. The first sign of pregnancy is the moment of implantation of the fertilized egg, which sometimes causes bleeding.

First trimester

The following sensations are typical for 1-3 months of pregnancy:

• Toxicosis of pregnant women. The body does not immediately accept the foreign body, which it considers an embryo, and begins to produce antibodies. Possible manifestations of intoxication - nausea, vomiting. There are other hypotheses that explain toxicosis, but experts do not have an exact answer as to why it occurs.
• Progesterone production increases, which sometimes affects well-being.
• The mammary glands swell and hurt.
• Dietary preferences change, sometimes previously favorite dishes cause rejection.

Second trimester

By the beginning of the second trimester of pregnancy, in most women, the manifestations of toxicosis disappear. Obstetricians call this time the most comfortable. The discomfort passes, and the volume of the abdomen does not yet become an obstacle to normal movements - it does not interfere with bending over to put on shoes, and the child’s movements are still too light and painless.

In first-time mothers, the belly grows more slowly and by the end of the second trimester, a pregnant woman may for the first time think about changing her wardrobe. In the second and subsequent pregnancies, the belly grows faster, but this also depends on the individual characteristics of the body. Some pregnant women experience heartburn. This is due to the growing uterus, which puts pressure on the internal organs and prevents the pancreas from working fully.

Third trimester

Starting from the 6-7th month of pregnancy, the belly grows faster, this causes some discomfort. From time to time, a woman experiences training contractions, which begin with a nagging pain in the lower back. In addition, the pelvic bones, in preparation for delivery, begin to diverge - pain in the perineum may occur, which intensifies during movement.

During this period, the number of fetal movements should be monitored, noting each movement on the pregnancy calendar. It is believed that a child should remind himself at least 10 times a day. A smaller number of movements may indicate pathologies. It is also important to monitor the discharge - bloody discharge may indicate the release of a mucous “plug” from the cervix, which occurs shortly before childbirth.

Critical periods of pregnancy

A woman carrying a child should listen to her body throughout the entire period, monitor her well-being, and avoid stress and excessive stress. However, there are periods of pregnancy when the threat of miscarriage increases. Obstetricians note several critical points:

• The most dangerous weeks of pregnancy in the first trimester are from 2 to the beginning of 4. During this period, implantation of the embryo may be disrupted due to a weak endometrium, fibroids, a cesarean scar, physical activity and stress.
• Dangerous periods during pregnancy in the 2nd trimester - 8-12 weeks. At this time, the placenta is actively developing, hormonal imbalances are critical, which lead to the risk of miscarriage. These are ovarian dysfunctions that do not produce enough of the hormone progesterone.
• 18-22 are extremely dangerous weeks during pregnancy. Chlamydia, toxoplasmosis, and herpes under certain conditions can cause disruption of the functioning of the placenta, infection of the fetus and miscarriage. A low location of the placenta also poses a risk of late miscarriage.
• There are also critical weeks of pregnancy at the end of the term - from 28 to 32. Pathologies such as late gestosis, placental insufficiency or abruption are possible, which can cause premature birth.

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