Pregnancy by trimesters: fetal development and woman's sensations. All trimesters of pregnancy by week, indicating the most dangerous periods Conventionally, pregnancy is divided into three

To understand and correctly monitor changes in the body, a woman needs a pregnancy calendar. In such a calendar, every week is scheduled, what changes occur in the body and you can track your weight gain, the weight of the baby and see the ultrasound readings.

Carrying a baby under your heart is an important event in the life of any girl. Pregnancy is always a mysterious and at the same time frightening event, and it is also a period of waiting for a miracle. From this article, you will learn what a trimester is and the features of each of them.

Terms of trimesters by week

On average, pregnancy lasts about 38-40 weeks and there are two designations for gestation periods: obstetric and embryonic. The first definition is used most often and is just 40 weeks, since it is sometimes very difficult to track the date of conception.
To understand and correctly monitor changes in the body, a woman needs a pregnancy calendar. In such a calendar, every week is scheduled, what changes occur in the body and you can track your weight gain, the weight of the baby and see the ultrasound readings. It is very good that in our modern world, there are a lot of electronic pregnancy calendars and you can choose the most comfortable calendar just for you.

How are the trimesters of pregnancy divided by weeks

The entire gestation period is conventionally divided into three trimesters. Trimester - three months. In weeks 38 to 42, that's 9 months. At 12 weeks, the 1st trimester ends, the second - at 24 weeks, the third lasts until the approximate date of birth. When determining the period, gynecologists are guided by the obstetric period, that is, the countdown starts from the last menstruation.

Features of each period

• The first trimester is very important, because at this time the body begins to rebuild to bear the crumbs. At this time, toxicosis often appears, hormonal failure, mood swings and increased fatigue are possible. In the first trimester, the fetus develops the nervous system.

• The second trimester is special in that at this time the signs of toxicosis disappear, and the stomach takes shape and begins to round. This trimester is considered the most calm.

• The third trimester is the hardest of all. The child already sees, hears, waves his arms and legs with a vengeance, as if showing that he is tired of being locked up. The baby has already become very heavy and it is difficult for the mother to carry him - his back, legs begin to hurt, fatigue piles up many times more. The mood is often decadent and mommy prefers to stay at home or sleep than to go out to people - and this is normal.

Child development by trimesters of pregnancy

After the female egg has merged with the male, a clot of cells is created in one shell, within a week this clot should reach the uterus and gain a foothold there. This whole process takes place during the first month of pregnancy. When the fetal egg attaches to the wall of the uterus, the embryo will begin to develop at an accelerated pace. At week 7, it already outwardly resembles the outlines of a little man, although it is still quite tiny. Until the end of the first trimester, that is, up to 12 weeks, all organs and systems are formed. On days 21-22, when the embryo is about 3 weeks old, his heart begins to beat. Outwardly, it still does not look the same as in adults, but it already fulfills its function. By the end of the second trimester, the baby receives the status of a fetus and is already completely similar to a person, all organs and systems are formed in him, they gradually begin to work. During the third trimester, the unborn child only grows, gains weight and "ripens". The nervous system, digestive system and brain continue to improve after birth.

Changes in the female body by trimester

Immediately after conception, the female body begins to change in such a way that the baby survives and can be born. To do this, a hormonal boom occurs, the level of progesterone in the blood rises, which throughout the pregnancy "adjusts" the female body to the presence of the fetus and suppresses the immune system so that it does not get rid of the child.
The most striking reaction to hormonal changes is nausea and vomiting. Toxicosis usually begins at the end of the first trimester. Each woman individually lasts toxicosis, but for most it stops by the second trimester. By the end of the 2nd trimester, the stomach is already becoming noticeable, the chest is increasing several times.
The third trimester - it is already difficult for a woman to move around a lot, it is difficult to get enough sleep, she wants to get rid of the burden as soon as possible. The body throughout pregnancy prepares for labor. In the last trimester, there are training contractions that resemble real ones, but are not as painful and do not last long, only from time to time. The uterus has increased more than 500 times compared to the first weeks of pregnancy. Age spots appear, areolas darken, skin dries and itches, hair, nails and teeth deteriorate. All due to the fact that the baby needs a lot of nutrients and he takes them from the mother's body. Therefore, during gestation, it is necessary to eat well, and most importantly, eat right. If the deficiency of some vitamins and microelements is too noticeable, then you need to add vitamin complexes, they are prescribed by a doctor.

Prohibitions in each trimester of pregnancy

What is dangerous 1 trimester

At this stage, the most dangerous thing is miscarriage and infectious diseases. At the beginning of pregnancy, it is important to give up bad habits. Switch to a balanced diet. During toxicosis, drink more fluids, consume high-quality foods, eat in small portions, but more often 3 times a day, do not overeat at night, it is generally not advisable to overeat. Monitor your well-being, immediately respond to heavy bleeding and sharp pain. Try to be less in crowded places, use all precautions during epidemics of colds.

What is dangerous 2 trimester

In the second trimester, you need to pay special attention to:

• Allocations, if their character changes, there is pain when urinating, itching, swelling of the genital organs. The color becomes green, brown or yellow. Curdled discharge is also a deviation from the norm and requires intervention. Help is urgently needed if blood appears, even in small quantities.
• Strong pains. Head, abdomen, legs, pelvis.
• Violation of vision.
• Puffiness. The legs or face began to swell.
• Excessive weight gain.
• Frequent nausea or vomiting.
• Fever, chills, significantly elevated body temperature.

You should also consult a doctor if you cough up blood and it becomes difficult to breathe.

What is dangerous 3 trimester

In the last trimester, preterm birth can be dangerous, especially in the first half of the trimester up to 36 weeks. An early labor activity is indicated - a short cervix, leakage of amniotic fluid, increased uterine tone, labor pains, heavy bleeding. You should also monitor the activity of the baby, if he is excessively active or vice versa, you need to undergo an examination.

Nutrition during pregnancy by trimester

• 1st trimester - When a woman finds out that a “bubbler” has wound up inside, you need to immediately review your diet and habits. Give up smoking and alcohol, not to mention other psychotropic substances. If the expectant mother takes serious drugs, then you need to determine the risks and what is better to refuse - drugs or pregnancy. With toxicosis, food should be light and well absorbed, contain all the necessary vitamins and minerals. It is right to eat meat and fish, especially low-fat varieties. Chicken eggs, a variety of cereals, vegetable salads seasoned with vegetable oils, dairy products, fruits and berries. Drink water, compotes, fruit drinks, natural juices.
• 2nd trimester - Follow the same diet. You can add more nuts, seeds, bran. Cook various dishes from cottage cheese, add grated hard cheese to soups. All dishes should be consumed boiled or steamed. Refuse fast food, smoked meats, pickled foods, sweet soda, fatty sweets, fresh pastries. Drink enough liquid.
• 3rd trimester - Continue to eat right, do not increase portions. If toxicosis worries again, then switch to lighter meals. When feeling normal, cook food in the oven, steam, or boil. Raw to eat some vegetables, fruits, herbs, berries. Porridges are obligatory to minimize the threat of constipation. Drink plenty of fluids so as not to provoke swelling, but at the same time observe the drinking regimen.

Each trimester has its own characteristics. The baby develops gradually. The task of the mother is not to harm the fetus while it matures inside, to think not only about herself, but also to take into account the needs of the unborn child.

Analyzes and procedures by trimesters

You need to register in the women's office in the first trimester, preferably before 10 weeks of pregnancy. From the moment of registration and until childbirth, a woman visits a gynecologist at least 2 times a month, if there are no problems with bearing. For the entire period, the following studies are carried out by trimesters:

• In the first trimester, a blood test is given for sexually transmitted diseases, including AIDS / HIV, a general blood test, urine. Another swab is taken from the vagina for tank tests. Blood for biochemistry and hormones, clotting tests. Double test for hCG and PAPP-A. Tests for antibodies to rubella and toxoplasmosis. Ultrasound examination shows where the fetal egg was attached, whether the embryo develops correctly, whether its development corresponds to the established norms and whether there are any deviations.
• In the second trimester, an ultrasound is performed - it will show how the baby develops, biochemical screening to identify the child's diseases, if any. Whether organs are formed correctly in him, the general condition of the placenta and uterus. Urine and blood are given - a general analysis. Blood for biochemistry, venereal diseases, hepatitis. Smear for infection. Triple test - hCG, AFP and the hormone estriol.
• In the third trimester, a repeated blood and urine test is taken, at each appointment with a doctor, ultrasound and CTG are performed. Up to 36 weeks, a smear for genital infections. Blood for HIV, hepatitis and syphilis. Biochemistry up to 30 weeks. Coagulogram and blood for antibodies to toxoplasmosis and rubella on the recommendation of a doctor. With the help of ultrasound, you can see the sex of the unborn child. How does he feel, is there any entanglement with the umbilical cord.

With the help of ultrasound, young parents can see the child in motion, and so consider every line of it and, subsequently, save these frames for a long memory. And the doctor will make sure that the fetus develops correctly.

The most detailed pregnancy calendar

The happiest time in the life of every woman - pregnancy - is divided into time stages: trimesters, months, weeks. Each of these units of time has the peculiarities of its course - both in the body of the expectant mother and in the body of the future baby. We will talk about all this in the most detailed and understandable way.

Living stories to help

In addition to medical (gynecological) information from experienced obstetricians, we will share with you the real stories of thousands of Babyblog mothers on the pages of our calendar. They are equipped with expressive photographs, ultrasound images, descriptions of sensations in one or another obstetric week of pregnancy. We will also give you tips and recommendations for each of the stages on the road to a miracle.

On the verge of a miracle

In order to receive a newborn carefully wrapped in a diaper for the first time, to hear its first cry, to smell its smell, you have to climb the happy ladder of forty steps - forty weeks. Not one of them stumble, do not grumble about fate, do not complain about ailments. On the top step of this amazing staircase, you will spread your wings and go on a magical flight of happy motherhood. The miracle is close at hand!

Listen to Experienced Moms

It is very important at the time of bearing a child not to worry once again, not to quarrel with loved ones, not to allow phobias and stress. It is for this purpose that each week of pregnancy in our unique calendar is accompanied by useful tips and good recommendations from experienced mothers who have gone through this path more than once. You will be calmer when at each time stage you can find out the experience of other mothers in this or that issue of your well-being and the healthy course of pregnancy.

How is the pregnancy going?

In the first obstetric week of pregnancy, the female body begins to prepare for possible fertilization, which will occur later.

In the second week, the "leader" in this cycle is determined - the egg, which will give rise to a new life.

As a rule, at the end of the second - the beginning of the third obstetric week of pregnancy, fertilization occurs - the fusion of a mature egg with the most nimble and persistent sperm from a huge number of applicants. As a loving man completely dissolves in the object of his passion, so the spermatozoon dissolves inside the parent egg. The genetic information of the parents is combined. Now a new life exists!

At the fourth week, the baby is a lump of rapidly dividing cells. When viewed under high magnification, the embryo resembles a raspberry.

At the fifth week of pregnancy, the laying of the most important systems begins. Now the heart, blood vessels and respiratory system are being formed - something that is vital for independent existence.

Next week, the future baby has a hint of arms and legs, separate parts of the inner ear and larynx are formed.

At the seventh week, the fetus actively develops the brain, the gastrointestinal tract begins to form, and the lungs form.

In the eighth week, the great sculptor - nature is engaged in fine work. Ears, nose and upper lip are now formed, as well as fingers on the hands.

At the ninth week of pregnancy, the back of the embryo will begin to straighten, and the tail will “dry out”. The baby's brain develops at a tremendous pace.

The laying of milk teeth begins next week. The embryo is now surrounded by amniotic fluid, protecting it inside from shock and shaking.

At the eleventh week, the unborn baby already has sexual characteristics, and with the help of modern equipment, future parents can now find out who is inside - a charming girl or a strong little boy. In addition, the color of the eyes is determined in the fetus.

By the twelfth week of pregnancy, the future baby has practically formed all the systems of the body. In the remaining time, they will grow and develop.

The thirteenth week ends the first trimester of pregnancy. The placenta is fully formed. Now she will be responsible for the delivery of nutrients and oxygen from mother to baby.

At 14 weeks, the baby is covered with a gentle fluff - lanugo. It retains a cheese-like lubricant, which in turn protects the baby from the surrounding waters.

It has been proven that already at the 15th week of pregnancy, the baby's tiny heart passes more than 20 liters of blood per day. The skin of the belligerent is thin and red, it is still so different from a well-fed baby.

At the sixteenth week, the fetal head is no longer so pressed to the chest, it gradually straightens. The muscles of the face are developed, so the child can wink and frown.

At week 17, "brown fat" begins to be deposited, which is necessary for the body's heat exchange. But there is still no subcutaneous fat.

At the 18th week of pregnancy, the baby can already hear you, as the structures of the middle ear are being improved. It's time to talk to the child and sing children's songs to him.

The following week, the limbs grow and become more proportional.

At the twentieth week, the puffer is a miniature man - with a delicate fluff on his head and tiny nails on his fingers and toes. He has a lot to do - the baby yawns, sucks his fist, somersaults.

In the twenty-first week, blood cells begin to be produced, which are responsible for protecting the body from infections. Thanks to the developed papillae on the tongue, the fetus feels the taste of the surrounding waters.

At week 22, the baby strokes his arms, legs, face, sucks his finger and pushes off the walls of the uterus with his legs.

At the twenty-third week, the fetus begins to store subcutaneous fat.

At the 24th week of pregnancy, the baby becomes larger and more well-fed. It occupies almost the entire uterus, it becomes more and more difficult to tumble.

The next week, bones are strengthened, joints are formed.

At 26 weeks, the baby is able to open his eyes.

The third trimester starts with the twenty-seventh week. A baby weighing approximately 1000 g has all the main systems working, although their development has not yet been completed.

At week 28, the brain grows, new cells and nerve connections are formed.

At the twenty-ninth week, the baby has already learned to more or less regulate its own body temperature.

At the thirtieth week, the baby's eyes are wide open, he reacts to the contrast light penetrating through the mother's tummy.

The following week, the baby reacts to loud noises and pain. You can feel it move as the doctor feels your abdomen.

At 32 weeks of gestation, the baby hears perfectly what is happening outside the tummy. He recognizes the beating of his mother's heart, bowel movements and the sound of blood flowing through the umbilical cord. That is why the baby calms down after birth if the mother presses him to her chest, because he hears the usual sounds of her heart.

At 33 weeks, the baby still has enough space for movement, but every day the space of the temporary house - the uterus becomes more and more cramped for him.

By the next week, subcutaneous fat is already a tenth of the baby's weight, which gives the skin of the fetus a smooth and pinkish tint.

From week 35, the baby will gain 200-220 grams weekly to his current weight (approximately 2550 g).

The next week, the baby's face became smooth, plump cheeks appeared.

At week 37, the baby is ready for birth and has taken its final position in the uterus.

At 38 weeks, the baby lost lanugo. There is less original lubricant.

At the thirty-ninth week of pregnancy, the walls of the uterus contract from time to time, "rehearsing" childbirth.

At the fortieth week, fetal movements slowed down in anticipation of birth. His intestines are filled with original feces (meconium). The appearance of the crumbs into the world should be expected at any time.

At 41 weeks of pregnancy, all organs and systems of the unborn child are ready to start independent work at any time.

At 42 weeks, the baby grew long nails on all fingers, hair. His eyes are open, he is becoming more active again.

In our calendar, each week of pregnancy, we will consider in as much detail as possible. Welcome!

Even the most inexperienced mom knows that in general, the pregnancy period is divided into three trimesters. After all, this way you can navigate with special convenience not only to specialists, but also to expectant mothers. It should be clearly understood that each period will be different.

Of course, those women who give birth not for the first time know how the trimesters of pregnancy are actually divided by weeks, but as for inexperienced mothers, this question remains a mystery to them.

Trimesters of pregnancy: features

It should be clearly understood that every mother should know that if she reads this information as a whole, thereby understanding what needs to be paid attention to, then you can always use your time wisely. Moreover, it becomes possible to avoid certain complications that sometimes have to be faced.

First trimester

The first trimester is the very period of time when a new life is born. Naturally, here a woman should take care of herself especially, protecting herself from various negative external factors. As a rule, so far there is no pregnancy, but the body is preparing for the fact that this will happen very soon.

Attention: This time is different in that a woman may not know that a new life is emerging in her body. Thus, sometimes there are various failures in the process of cell division, which leads to such a sad process as a miscarriage.

In addition, the future baby is faced with certain congenital pathologies.

But of course, you should not tune in to the negative; in practice, everything usually goes well.

Attention: The main feature of the first trimester is that it is at this moment that the baby's organs are formed. Therefore, it is necessary to forget about bad habits, you can not take those medicines that were allowed before pregnancy, etc.

Second trimester

As for the second trimester, it differs in that the condition of a woman changes dramatically. As a rule, at this moment the figure does not yet suffer any special changes, and if you do not tell others about your pregnancy, no one will know.

But a hormonal storm occurs in the body, and this leads to the appearance of unpleasant symptoms of toxicosis. This is due to the fact that the metabolism undergoes such changes so that the nutritional needs of the child can be met.

Pregnancy trimesters by week: table

Pregnancy trimesters by week table

Naturally, immunity also decreases during this period, which means that the body requires as many vitamins, bright and positive emotions as possible, remember this. In general, the second trimester is associated with a calm period for a woman.

This is due to the fact that the baby's organs are already formed, which means that you should not worry about the appearance of certain violations in the development of the crumbs. This period is also different in that now the woman's tummy is rounded.

third trimester

The third trimester is the final stage of pregnancy. Now the figure of a woman is changing dramatically, it will not work to hide the tummy from others, as it will reach its maximum size. Even if it were possible to perform this or that work, a woman cannot do this, which means that it is worth relying on the support of relatives.

The baby begins to gain weight, thereby taking up free space in the mother's stomach. It should be noted that this period can be dangerous for a future mother, because sometimes various complications arise, for example, hemorrhoids, varicose veins, etc.

To avoid such ailments, it is so important not to ignore the examinations prescribed by a specialist, paying special attention to yourself, not forgetting about proper rest, a quiet pastime.

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Almost every expectant mother has heard that the entire period of pregnancy is conventionally divided into trimesters. So it is much more convenient to navigate both doctors and pregnant women themselves, because each of these periods has distinctive features. At the same time, not every woman knows how the trimesters of pregnancy are separated by weeks.

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

Some experts believe that the first trimester ends at 12 weeks, others at 13. There are also disagreements about the time for the completion of the second trimester and the onset of the third.

Nevertheless, the most rational is such a point of view, 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 birth of the baby.

This division of pregnancy trimesters into weeks 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 is marked by the birth of a new life. This period begins on 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 in the programmed process of cell division may occur, as a result of which a miscarriage may occur, or any congenital pathologies may occur in the unborn child.

Fortunately, this happens quite rarely, therefore, subject to the successful course of pregnancy, the embryo develops very intensively.

Second trimester

During the first trimester, the physiological state of a woman changes dramatically. Despite the fact that the figure of a pregnant woman undergoes almost no changes, a real hormonal storm occurs in her body, as a result of which symptoms of toxicosis often occur. The entire metabolism is rebuilt in such a way as to meet the needs of the future baby in the necessary nutrients. Immunity during this period is somewhat reduced so that the embryo is not rejected 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 it is contraindicated for a woman to take almost all medicines, smoke, drink alcoholic beverages and indulge in other bad habits. It is necessary to lead a healthy lifestyle in order to prevent the appearance of pathologies in the unborn baby.

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

All the functions of providing the body of 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 it is permissible for a woman 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 during the second trimester of pregnancy usually feels great, because her body is already accustomed to the new state. At 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 onset of 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 dramatically, because the tummy reaches its maximum size. Now it is difficult for a woman to do physical work, so it is necessary to enlist the support of relatives and friends.

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

A future mother in the third trimester may experience some complications of pregnancy: late preeclampsia, hemorrhoids, varicose veins and other ailments. That is why it is necessary to pass the scheduled examinations on time and pay enough attention to yourself, not forgetting about rest and a quiet pastime.

Tests during pregnancy by trimesters

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

The first trimester involves the following examinations:

• general blood analysis;
• a blood or urine test for hCG (human chorionic gonadotropin) upon registration to confirm the fact of pregnancy;
• general urine analysis;
• blood chemistry;
• vaginal swab to detect bacterial infections;
• a blood test to detect certain infections (hepatitis, HIV, rubella, etc.);
• a blood test for the determination of Rh antibodies with the existing probability of developing a Rh conflict.

Screening of the first trimester is a comprehensive examination, which is carried out for a period of 11-13 weeks, consists in determining the level of certain substances in the blood: hCG, as well as PAPP-A, that is, plasma protein-A associated with pregnancy. In addition, the screening examination includes an ultrasound of the fetus. Based on the screening results, the risk of genetic abnormalities in the fetus is revealed. If the probability of anomalies is too high, a woman is recommended to undergo an additional examination by a geneticist.

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

• regular blood tests, urine;
• blood chemistry;
• measurement of a woman's body weight, abdominal circumference, standing height of the fundus of the uterus and other indicators;
• second trimester screening.

This comprehensive examination consists of performing a blood test for a period of 16-20 weeks in order to determine the content of certain hormones, as well as performing an ultrasound scan of the fetus. In the blood, the level of free estriol, as well as AFP (alpha-fetoprotein), is established, and the level of hCG is re-determined. During the ultrasound, the specialist measures the parameters of the fetal body and compares them with the standard indicators placed in special tables. Based on the results obtained, the risk of the fetus having certain genetic abnormalities 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 the examinations are aimed at determining the condition of the fetus and identifying possible complications in the later period. The complex of surveys includes:

• repeated blood test for the detection of antibodies, some dangerous infectious diseases (hepatitis, HIV, etc.);
• urine analysis is performed several times in order to detect possible signs of preeclampsia;
• smear from the vagina;
• screening of the third trimester, which consists in conducting the next ultrasound of the fetus. During the examination, the specialist determines the size of the child, pays attention to the degree of development of his organs, specifies the presentation of the fetus, 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 from the relevant specialists.

Each of the trimesters of pregnancy is beautiful and wonderful in its own way. At first, a woman rejoices at the birth of a new life, trying to adapt to a new state for her. 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 miraculous event of the birth of a baby will happen very soon, and this gives strength and confidence to the expectant mother.

Gynecologists conventionally divide the entire period of gestation into trimesters of pregnancy. One such time period includes 3 calendar months. Each period has its own characteristics of the development of the baby. In order to assess how the pregnancy proceeds, doctors compare these indicators with the norm.

How are the trimesters of pregnancy counted?

It has been established that, on average, the period of bearing a baby from the moment of conception to birth is 38-40 weeks. This difference is due to different methods of calculation: obstetric and embryonic. In practice, doctors use the first one, counting the duration of pregnancy from the date of the last menstruation. With the embryonic method, the period is calculated from the moment of conception.

In obstetrics, doctors calculate the duration of pregnancy in 40 weeks. Based on this indicator, the entire gestation period is usually divided into 3 trimesters.

If we consider specifically the trimesters of pregnancy by weeks, then such a division will look like this:

• 1 trimester - 1-13 weeks;
• 2nd trimester - 14-27 weeks;
• 3rd trimester - 28 weeks until delivery.

Fetal development by trimesters of pregnancy

Young women are often interested in how the child develops through the trimesters of pregnancy. For many, this process is comparable to magic, when a full-fledged organism develops from just two germ cells. By the time of birth, all the organs and systems of the baby are fully formed, but some of them are in their infancy. The body itself continues to grow and improve even after birth.

Fetal development in the first trimester

The first trimester of pregnancy is the most important and difficult of all. Directly at this stage, all the axial organs of the future baby are laid, and the further development of the fetus will depend on the correctness of the course of these processes. In some cases, a violation of the process of embryonic development leads to the death of the embryo, which ends in spontaneous abortion, so this is the most dangerous period of pregnancy.

In order to understand what changes the fetus undergoes when the first trimester is underway, let's name its main points by week:

• 1–2 weeks- the body is actively preparing for conception: the egg matures and ovulates, which occurs by the end of the second week;
• 3 week- the fetal egg reaches the uterus and is fixed in the endometrial layer;
• 4–5 weeks- the formation of the neural tube, which will then give rise to the nervous system. At this time, the heart begins to contract in the fetus;
• 6–7 weeks- the spine, cerebral hemispheres, the front part of the skull are actively formed: eyes, auricles, as well as the liver, stomach, thyroid and pancreas;
• 8–9 weeks- the rudiments of the genital organs, intestines are formed;
• 10–13 weeks- the baby begins to carry out the first movements, nails appear on the fingers. The heart is fully formed, the endocrine system begins the synthesis of hormones.

Fetal development in the second trimester

The second trimester of pregnancy is an active continuation of the process of fetal development. The nerve cells of the baby at this stage are already able to perceive and analyze information received from the external environment. The fetus learns to perceive sounds, to feel the space around it. The hematopoietic organs synthesize erythrocytes and platelets, the urinary system begins to work. By the end of the 13th week of development, ligaments and muscles begin to actively develop. Changes are also observed in the skeletal system: by this time, the fetus in its infancy has 20 milk teeth.

During the 2nd trimester of pregnancy, the baby changes outwardly. The first small hairs appear on the surface of his body - lanugo. They protect the body from overheating or hypothermia. As the date of birth approaches, the lanugo disappear completely, remaining in small numbers on the shoulders. The skin of the baby at this stage is still very thin, so blood vessels are visible through them. They give the skin a bright red tint. By the end of the second trimester, the fetus has a body length of 15-16 cm, and its weight is 135 g.

Fetal development in the third trimester of pregnancy

When it begins, there is a rapid maturation and improvement of the nervous system. Nerve fibers are gradually covered with a myelin sheath. In the brain, there is an increase in the number and depth of convolutions. This contributes to the normal functioning and development of the sense organs.

By this time, the baby hears well, feels the taste, is able to recognize the mother's voice. By week 32, there is a significant weight gain. The baby accumulates a large supply of subcutaneous fat. The kidneys and liver are finally formed. The weight of the baby by 32 weeks reaches 1700 g, height - 40–41 cm.

pregnancy weight by trimester

With an increase in the gestational age, the body weight of the expectant mother also increases. For the 1st trimester of pregnancy, weight gain is insignificant: there are practically no external signs, the stomach is slightly rounded. In order to control the gestation process, every expectant mother must take into account the weight gain rates, which are scheduled for weeks and trimesters. For all trimesters of pregnancy, a woman gains 8–14 kg (10–12 kg is the average). In general, weight gain depends on the following factors:

• body type of a woman;
• features of the diet;
• the rate of metabolic processes in the body.

Obstetricians pay special attention to the rate of weight gain by the expectant mother. Normally, this should happen like this:

• 1 trimester of pregnancy - 1-2 kg;
• 2nd trimester - 250-300 g weekly (3-4 kg in total);
• 3rd trimester - 3-4 kg.

Nutrition for a pregnant woman in trimesters

At different periods of pregnancy, the female body needs additional inclusion in the diet of additional products and substances. The opinion of those women who are sure that with the onset of pregnancy they need to consume 2 times more food is erroneous. Experts have found that in order to fully cover the nutritional needs of a pregnant woman, it is necessary to increase the calorie content of her diet by 20%. So, in the first half of pregnancy, the expectant mother should consume 2500 kcal, and in the second - 2900.

Special attention is paid to the diet. There are doctors recommend at least 5-6 times a day, in small, fractional portions. The break between meals should be 3 hours. It is important to monitor weight gain. Every week it should increase by 250–300 g. However, it is also necessary to take into account the initial constitution of the body of the pregnant woman. Thin women can gain 14 kg during pregnancy, while full women are allowed to add 7–9 kg so as not to increase the load on the body and the fetus.

Nutrition for a pregnant woman in the first trimester

Nutrition in the first trimester of pregnancy should be as balanced and healthy as possible. Directly during this period, the laying of the internal organs of the baby takes place. The food you eat should be rich in vitamins. Particularly important at this stage of gestation are:

• vitamin B9 - found in the liver, spinach, legumes;
• vitamin B12 - found in meat, dairy products, egg yolk;
• zinc - it contains sprouted cereals, seafood.

Nutrition for a pregnant woman in the second trimester

The 2nd trimester of pregnancy is characterized by rapid development and growth of the fetus. The baby's internal organs and systems are actively functioning. For their proper functioning and development, a constant supply of vitamins and minerals is required with food. Doctors recommend that expectant mothers pay special attention to iron and calcium. For normal fetal growth, a mother should consume 1200–1500 mg of calcium daily. This microelement is present in such dairy products as:

• cottage cheese;
• cheeses;
• milk.

In order for calcium to be fully absorbed by the body, and the second trimester to proceed without complications, it is important that there is a sufficient amount of magnesium and phosphorus. They are found in:

• fish;
• eggs;
• meat;
• bread;
• fresh vegetables.

To prevent the development of iron deficiency anemia, it is important to consume the right amount of iron. This trace element is found in sufficient quantities in:

• turkey;
• veal;
• beef.

Nutrition for a pregnant woman in the third trimester

The 3rd trimester of pregnancy is a period of active preparation of the body for the upcoming birth, so it is important to pay attention to the correct combination of proteins, carbohydrates and fats in the diet. The daily menu of a pregnant woman should contain complete proteins, which are a good building material for a growing fetus. A large amount of protein is found in dairy products of low fat content. To saturate the body with carbohydrates, it is recommended to eat foods rich in dietary fiber:

• cereals;
• whole wheat bread;
• bran.

Screenings by trimesters of pregnancy

Screening is a comprehensive examination aimed at establishing possible abnormalities in the development of the fetus. The study is carried out three times, 2 times in each trimester:

1. In the first trimester - 3-4 weeks of pregnancy (implantation), 8-12 weeks (hormonal changes in the body of the pregnant woman).
2. 2nd trimester - 18-22 weeks (active growth of the uterus can cause abnormalities in the attachment of the placenta).
3. Third trimester - 28-32 weeks (high risk of developing late preeclampsia, placental insufficiency, placental abruption).