9,10,11,12 weeks of pregnancy: what happens, development of pregnancy and fetus

23.08.2020 14935 0

The twelfth week of pregnancy is the end of the first trimester according to the obstetric period. In ten weeks of embryonic development, which are counted from the moment of conception, the child has made a huge leap from a fertilized cell to a practically formed human body. In the life of the expectant mother, there comes a time of peace and positivity, when the mood evens out and attacks of toxicosis recede.

Interesting Facts

Your baby is the size of

Kiwi

60-80mm Size

10-14 g Weight

Congratulations! You have passed the first milestone. You are 12 obstetric weeks pregnant. How much is this? You are in the 3rd month of gestation, the 2nd trimester begins. If you count the period from conception, then you have 10 weeks of gestation. What happens to mother and baby at this time? How does the fetus develop? What tests should a woman undergo? First things first.

Embryo 20 weeks - 30 weeks

During this period, the child can react to external stimuli. If the mother experiences excitement or nervousness, the fetus pushes hard. Such effects can sometimes be extremely painful. By the end of the period, weight can be up to one and a half kilograms, and height up to 40 cm. Fatty tissues, nerve connections, and immunity are formed in the body. Imprints appear on the fingers, the brain is actively developing. The lungs can function normally during premature birth.

Feelings of the expectant mother

The 1st trimester is ending, the most unpredictable and dangerous in terms of the risk of miscarriage. The baby has already “settled in” in the womb, and the expectant mother’s body has become accustomed to its new position. Most often, a woman at this stage of pregnancy feels good: the symptoms of toxicosis go away or have already disappeared, and emotional excitability has decreased.

What happens to a woman's body?

• The uterus has grown to 10 cm in width and has shifted somewhat into the abdominal cavity. Therefore, the urge to urinate becomes less frequent.
• Normal weight gain is 1.5-3 kg. The belly is not yet growing or growing slightly: it all depends on the general structure of the body and the number of pregnancies.
• A decrease in the amount of progesterone can affect the condition of the skin: dryness, flaking, acne.
• The first swelling may appear. Under the influence of hormones, the sodium content increases, which attracts fluid.
• The heart rate increases, which is associated with an increase in blood flow and increased load on the heart.

But there is also a nice bonus. Due to the high concentration of estrogen, the condition of the hair significantly improves: it becomes thicker and more voluminous.

Tenth week for baby

This week is important and significant; it is from here that the fetal stage of development begins, and the unborn child is now officially called a fetus, not an embryo. All the internal organs have already been laid down, which in the future will only have to grow and develop. Experts rightly consider the tenth week to be the final week in the first critical period: from this time on, the likelihood of developing defects that may arise as a result of chemical factors of various natures is no longer so high.

At this time, the fetus is freely located in the uterine cavity, without practically touching its walls. The unborn baby undergoes intensive formation of the nervous system, the transmission of impulses through the neuromuscular pathways is improved. This process leads to intense movements. Such movements are reflexive, they are active and caused by contact with the walls of the uterus. The fetus already makes fairly clear movements with its legs, head and arms. The woman is not yet able to feel the movements of the fetus, but during an ultrasound examination they are clearly visible.

At this time, the diaphragm is finally formed - a flat muscle designed to separate the abdominal and thoracic cavities. Further development of internal organs occurs.

What does a fetus look like at 12 weeks?

The size of the baby at 12 weeks of pregnancy is up to 6-8 cm from crown to tailbone, its approximate weight is 10-14 grams. He is already actively moving, although the woman cannot yet feel it. Facial features and facial expressions are more clearly visible: the child opens and closes his mouth, closes his eyes. Its structure is still disproportionate, the head is much larger than the body.

All organs and systems are rapidly developing:

• the muscles of the larynx master swallowing movements;
• taste buds begin to function;
• sucking and grasping reflexes appear;
• the retina, lens and cornea of ​​the eye are forming, but the baby’s eyelids are still completely covered;
• nail plates are formed, the first hair coat appears on the body - lanugo;
• The inner part of the ear is formed.

At week 12, the fetal genital organs are already formed, but during the first ultrasound you are unlikely to be told the gender of the unborn child due to the high risk of error. The baby is practicing breathing movements. The kidneys are already working, producing urine, which enters the bladder and is excreted into the amniotic fluid. Calling a baby an embryo at 12 weeks is incorrect. This is a full-fledged fruit.

First ultrasound in early pregnancy (up to 11 weeks)

Ultrasound examination of pregnancy from A to Z

An ultrasound can not only determine the presence of pregnancy, but also monitor the growth and development of the baby.
Ultrasound examination is the only method to detect fetal malformations. The study allows you to timely detect a frozen pregnancy, ectopic pregnancy, establish the cause of bleeding, and suspect the presence of a chromosomal pathology in the fetus (for example, Down's disease). The safety of ultrasound during pregnancy is confirmed by research from the American Institute of Ultrasound in Medicine, during which no changes were found in mammalian tissues and cells when exposed to ultrasound. Using this method for more than 30 years, there was no evidence of any complications in the fetus.

Fetal ultrasound has become firmly established in clinical practice. We provide you with information about what an ultrasound scan should include at different stages of pregnancy and what result you should get after undergoing this study.

The first ultrasound in early pregnancy is usually performed using a transvaginal probe. At 6-10 weeks of pregnancy, an ultrasound makes it possible to establish that this pregnancy is progressive (i.e., the fetus has a normal heartbeat), develops inside the uterus (i.e., exclude the dire diagnosis of ectopic pregnancy), and determine the number of fetuses. This study is recommended for those women who have had spotting during this pregnancy, or have had a previous miscarriage, missed abortion or ectopic pregnancy.

At 11 weeks the fetus is of sufficient size that a detailed assessment of its major anatomical structures can be made. During these periods, severe fetal malformations that are incompatible with life or lead to severe disability can be diagnosed.

This is how the coccygeal-parietal size of the fetus is measured in the first trimester

Fetal hand at 12 weeks of pregnancy

From 11 to 13 weeks, ultrasound markers (signs) of chromosomal pathology of the fetus can be detected - an increase in the thickness of the fetal nuchal space and the absence of the nasal bone during ultrasound.

Fetal nuchal translucency thickness (FNT) is the size of the area between the fetal skin and the soft tissues surrounding the cervical spine. The nuchal space is detected in fetuses both normally and with chromosomal diseases (for example, Down's disease), but fetuses with chromosomal diseases are characterized by an increase in the thickness of the nuchal space by more than 2.5 mm. The nuchal translucency in all fetuses disappears spontaneously after 14 weeks of pregnancy, so it is very important to have a study done from 11 to 13 weeks of pregnancy, when it can be measured.

The nasal bone is normally determined by ultrasound from the 10th week of pregnancy. In fetuses with chromosomal pathology, ossification processes occur later, so the absence of the nasal bone during ultrasound examination at this time may be a sign of chromosomal pathology of the fetus.

The physician must be highly skilled in assessing these signs, since obtaining the necessary views of the fetus in early pregnancy requires experience and technical skill. To measure TVP, you need to obtain the following image:

In the ultrasound photo of a pregnant woman, only the head and upper part of the fetal body are visible, the profile, nasal bone and TVP are clearly visible. Quite often you can see such incorrect images:

In these images, the fetus lies crookedly, the image magnification is insufficient, and a clear profile of the fetus cannot be seen. Measuring TVP in such images is INCORRECT and leads to an overestimation or underestimation of the risk of Down syndrome!!!

In addition to measuring the thickness of the nuchal translucency and assessing the nasal bone, several other markers have been proposed: assessment of blood flow through the tricuspid heart valve and through the ductus venosus, as well as measurement of the fetal facial angle. The assessment of these markers requires highly qualified physicians, and is possible only after obtaining international certification for each marker.

Typically, blood in the fetal vessels flows in one direction: from the heart to the peripheral vessels. If there is a chromosomal abnormality in the fetus or heart defects, the direction of blood flow may change, and in some phases of the cardiac cycle, blood begins to flow back to the heart.

Normal blood flow in the fetal ductus venosus at 12 weeks of pregnancy

Reverse blood flow in the fetal ductus venosus at 12 weeks of gestation

Registration of blood flow through the tricuspid valve of the heart and through the ductus venosus (this small vessel is present only in fetuses; during the newborn period, the blood flow in it stops and it closes) allows us to identify up to 65% of fetuses with Down syndrome. In 1-3% of normal fetuses we may also see reversed flow in the ductus venosus or tricuspid valve, so these findings must be assessed in conjunction with other ultrasound findings.

Normal blood flow through the tricuspid valve of the fetal heart at 12 weeks gestation

Pathological reverse blood flow through the tricuspid valve of the fetal heart at 12 weeks of pregnancy

Measuring the fetal facial angle is based on the fact that the faces of patients with Down syndrome are wider and flatter than those of normal people. The same pattern is observed in fetuses with this disease. By measuring the angle between the frontal bone and the upper jaw of the fetus, an objective conclusion can be made about the presence of a flattened profile in the fetus; this marker is present in 60-65% of fetuses with Down syndrome in the 1st trimester of pregnancy.

Method for measuring the facial angle of the fetus at 12 weeks of pregnancy

If the necessary standards are met, an ultrasound examination at 11-13 weeks of pregnancy assessing the thickness of the nuchal translucency, nasal bone, facial angle, blood flow through the tricuspid valve and ductus venosus can identify up to 80% of fetuses with Down's disease and other chromosomal diseases, and in combination with biochemical screening allows you to increase the diagnostic efficiency to 85-90%. It should be emphasized once again that the assessment of these markers requires a highly qualified doctor and is possible only after undergoing appropriate training and certification.

Ultrasound examination at 11-13 weeks of pregnancy is currently the most effective way to prevent the birth of a child with Down syndrome or other chromosomal diseases.

Scheme for measuring the thickness of the collar space

And this is what the fetus looks like on three-dimensional images (3D/4D ultrasound) in the first trimester:

We hope that this information will help you better understand why we are conducting this study, and why it is important to conduct it specifically from the 11th to the 13th week of pregnancy.

At 18-22 weeks of pregnancy, the fetus reaches a mass of 400-500 grams and a length of 22-27 cm. With such dimensions, an ultrasound examination makes it possible to examine in detail all the anatomical structures of the fetus and identify the majority of malformations that require surgical correction or lead to a deterioration in the child’s quality of life. In addition, this ultrasound scans for markers (signs) of Down's disease and other chromosomal diseases. The appearance of many fetal organs with Down syndrome has slight differences from the appearance of normal organs, and a comprehensive assessment of all anatomical structures makes it possible to assess the risk of the fetus having Down syndrome and, if necessary, recommend in-depth diagnostics (using invasive methods) of this disease.

After an ultrasound scan at these times, most questions of prenatal diagnosis are considered closed.

In addition, an ultrasound at 18-22 weeks assesses the amount of amniotic fluid, the position and structure of the placenta. The transvaginal sensor can accurately measure the length of the cervix and thus determine the risk of premature birth. This study is especially recommended for women who have already had premature birth, cervical surgery, and also with multiple pregnancies.

2D profile of a fetus at 20 weeks of gestation

Fetal spine at 21 weeks of gestation in 2D mode

Fetal heart chambers at the 22nd week of pregnancy in 2D mode

Ultrasound of the fetus at 21 weeks and 4 days in 3D mode

The main task of ultrasound at 32, 33, 34 weeks is to measure the circumference of the head and abdomen, the length of the bones of the limbs, and calculate the estimated weight of the fetus. This allows us to predict whether spontaneous birth is possible, whether there is a delay in fetal development or its disproportionate development.

In addition, ultrasound at 32-34 weeks allows:

• evaluate the appearance of the placenta and ensure that its position in the uterus does not interfere with normal labor
• measure the amount of amniotic fluid and exclude polyhydramnios and oligohydramnios
• assess the location of the fetus in the uterus (cephalic, pelvic or transverse)
• assess blood flow in the fetal and umbilical cord vessels using Doppler ultrasound to ensure that the fetus is receiving sufficient oxygen and nutrients

Fetal face in 3 projections in 2D mode and its three-dimensional (3D) reconstruction

A conventional ultrasound is a series of two-dimensional flat images of the fetus or its individual organs.

3D (3D) ultrasound is a method of obtaining an image, which is achieved by complex transformation of the obtained two-dimensional information into a three-dimensional three-dimensional model. Transformations are carried out using a special three-dimensional sensor and computer programs included in the ultrasound machine. The resulting volumes can be rotated and viewed from different angles.

4D (4D) ultrasound is the acquisition of a three-dimensional image of the fetus and its movements in real time. Thus, in addition to the three-dimensional image of the fetus, a fourth dimension is added - time, and it is possible to consider the motor activity and facial expressions of the fetus in motion.

Ultrasound in 3D and 4D modes can be done at different stages of pregnancy, but the result and quality of the image primarily depends on the position of the fetus in the uterus, the amount of amniotic fluid in front of its face, the presence of obstacles in the path of the ultrasound wave (uterine fibroids, uterine scar, subcutaneous tissue may obstruct examination and reduce image quality). So, if the fetus lies close to the wall of the uterus, then it is almost impossible to obtain a three-dimensional image of its face, just as it is impossible to see the face of a person who has rested his head against the wall. Sometimes you have to wait 15-20 minutes and continue the study after changing the position of the fetus.

The optimal period for obtaining an image of the fetal face is 20-26 weeks of pregnancy. At these stages, the fetus often changes its position, and there is enough water around it to see the face and body. After 30 weeks of pregnancy, the fetus is so large that it has to cluster well to fit in the uterus. However, obtaining a beautiful three-dimensional image of the face can be difficult and even impossible - it all depends on the position of the fetus.

It is important to understand that 3D/4D ultrasound is performed in addition to regular fetal ultrasound and cannot completely replace it. Measuring the size of the fetus and excluding malformations is carried out using conventional two-dimensional ultrasound. Only for some malformations does the use of three-dimensional ultrasound provide the doctor with additional information.

3D ultrasound of the fetus at 11 weeks and 4 days

3D ultrasound of the fetus at 21 weeks and 4 days

Ultrasound during multiple pregnancy

A multiple pregnancy is considered a high-risk pregnancy for various complications for the mother and fetus, since a woman’s body is more designed to carry one fetus. Therefore, during multiple pregnancies, it is necessary to conduct ultrasound more often and monitor the growth and development of the fetus. There are several types of twins, depending on the number of placentas and membranes.

Dichorionic diamniotic twins are the most favorable type of twins. Each fetus has its own placenta and its own amniotic space, separated from the other by the amniotic septum. The fruits can be of the same or different sex. The probability of delayed development of one of the fetuses is 20% (4 times higher than in a singleton pregnancy), premature birth is 5% (1% in a singleton pregnancy). In order to promptly identify these complications, it is necessary to conduct an ultrasound at 11-13 weeks, 18-22 weeks (as in a singleton pregnancy) and then every 4 weeks until birth (in a singleton pregnancy - at 32-34 weeks). If any complications are detected, the number of ultrasound scans may increase.

Monochorionic diamniotic twins - occurs when a fertilized egg splits into two parts. In this case, the fetuses have one common placenta and their own amniotic space. The fruits are always the same sex and completely genetically identical. The presence of a single placenta can lead to the development of specific complications associated with the fact that the vessels in this placenta can connect the circulatory systems of both fetuses. In this case, one fetus receives some blood from another fetus, and they both suffer from this: one has excess blood, which leads to increased stress on its heart; the second does not receive enough blood, oxygen and nutrients, and begins to grow more slowly, as a result of which it develops intrauterine growth retardation. This complication is called feto-fetal transfusion syndrome, and without timely treatment can lead to the death of one or both fetuses. In order not to miss this complication, it is necessary to do an ultrasound at 11-13 weeks (as in a singleton pregnancy), at 16, 18, 20, 22, 24, 26, 28 weeks of pregnancy. If signs of feto-fetal syndrome are detected, ultrasound should be performed even more often - once a week. If there are no signs of this syndrome before 28 weeks of pregnancy, then its development in the future is extremely unlikely, and ultrasound can be performed once every 4 weeks - as with dichorionic twins.

Monochorionic monoamniotic twins - occurs when a fertilized egg is divided into two parts, while the fetuses have a common placenta and a common amniotic space.
The fruits are always the same sex and completely genetically identical. This is an extremely rare type of twins, and is accompanied by the greatest risk of complications, developmental delay and intrauterine death. In addition to the complications associated with a single placenta (see description above), the fetuses are located in a common amniotic space and are not separated by the amniotic membrane. This can lead to torsion and compression of their umbilical cords, stopping the flow of blood to one of them and, accordingly, its death. The risk of this complication is very high, so an ultrasound is performed every week of pregnancy, and if signs of umbilical cord torsion are detected, hospitalization and daily monitoring of the fetus are recommended; If the condition of one of the fetuses becomes critical, immediate delivery by cesarean section is required. Back to articles

Tests and ultrasound

Now is the optimal time for testing for fetal pathologies, or first screening. It detects genetic abnormalities in development. Knowing about the condition of the fetus, the woman and the medical staff can specially prepare for the birth of a special baby, or the woman still has the opportunity to terminate the pregnancy at this stage.

How to do screening at 12 weeks of pregnancy

The woman takes a blood test for the hCG hormone and PAPP-A protein, then an ultrasound examination is performed. Laboratory data and ultrasound results are entered into a special program that calculates risks taking into account the age of the expectant mother, the number of pregnancies, lifestyle (whether she or the expectant father smokes), and concomitant diseases. As a result, you receive a form where the risks of various chromosomal disorders in the fetus are indicated in percentage terms. A gynecologist will help you decipher the data.

Eleventh week for baby

The fetus continues to grow rapidly in the eleventh week. Externally, it looks like this: a fairly large head, small legs pressed to the tummy, a small torso and well-developed long arms. This uneven development is due to the fact that throughout the entire previous period it was the upper part of the body, in which vital organs such as the heart and brain are located, that received the bulk of nutrients and oxygen.

The fetus continues to form joints and bones and grow muscles. Not only large joints develop, but also small ones. The rudiments of teeth form in the jaws, and nails form on the fingers.

The movements of the unborn child become more and more purposeful. Loud sounds and sudden movements begin to provoke a response from him. Grasping and sucking reflexes develop - this can be seen by the movement of the fingers and lips. The formation of olfactory and taste receptors begins. If amniotic fluid enters the nose or mouth, the fetus is able to taste it.

At this stage, the formation of the iris of the eyes also occurs, which after birth will determine their color. In most cases, newborns have blue or blue eyes; brown ones are quite rare. The final color of the iris is formed by five months. It depends on the accumulated melanin pigment located in the iris. Genetic inheritance determines the amount of this pigment.

Possible complications

At the twelfth week, a woman may experience the following unpleasant symptoms.

Unusual vaginal discharge

Normally, they should be light, whitish, with a slight sour odor. Mucus, pus, blood clots are symptoms of an inflammatory process. Usually accompanied by itching or a burning sensation.

Pain in the lower back and pelvic area

Caused by stretching of the ligaments that hold the uterus, as well as congestion due to a sedentary lifestyle. If pain does not bother you constantly and disappears when you change position or after self-massage, do not worry. If they are intense and accompanied by unusual discharge, such as brown or pink, you should seek medical help.

Decreased immunity and high risk of ARVI

Susceptibility to colds during pregnancy is explained by a lack of vitamins against the background of toxicosis, iron deficiency, and disruption of sleep and rest patterns. To protect yourself from complications, get a flu shot, and during the epidemic season, spend less time in crowded places. If you have a high temperature, you should call your doctor and tell him about your situation, since not all anti-fever medications are safe during pregnancy.

Dangerous symptoms

It is believed that until the twelfth week, healthy children are born and the danger of miscarriage due to gross pathologies has already passed. Nevertheless, you should carefully monitor your condition.

Stomach ache.

They remain an alarming symptom. Hypertonicity of the uterus with pain in the rectal area may be a sign of a threatened miscarriage.

Bleeding.

Scarlet blood is the first sign of an incipient miscarriage. Call an ambulance immediately.

Brown discharge.

Abundant brown discharge accompanied by increasing abdominal pain may indicate fetal rejection. This situation is dangerous for the development of inflammation and sepsis.

Do's and Don'ts

The twelfth week of pregnancy is a period when appetite significantly improves. But this does not mean that now you should start eating for two. Make sure your diet is balanced. It must include protein products: meat, fish, dairy products. The latter are also beneficial due to their high calcium content.

Include sources of vitamins and microelements in your menu: vegetables and fruits, legumes, nuts, various vegetable oils. This is the best prevention of constipation, which pregnant women are prone to.

Checklist for 12 weeks of pregnancy

• If before the 12th week, flights could worsen the condition of the mother and fetus, then in the second trimester you can travel without fear.
• Start doing Kegel exercises to strengthen your pelvic floor muscles. This is an excellent prevention of involuntary urination during pregnancy and after childbirth.

Still have questions? You can always consult with specialists at the Women's Medical Center. We provide comprehensive pregnancy management and also perform 1 fetal screening based on the Delfia-LifeCycle system, the accuracy of which is 98%.