Prenatal development of the baby on trimesters

The child begins to develop from one fertilized egg, which can be seen only under a microscope. For the nine months of a single cell to grow a child weighing about three kilograms. Is not it a miracle? So what happens in a woman's body as her baby grows?

I trimester of pregnancy, 12 weeks - the beginning of a child's development

Once arrived Conception Conception, ovarian cycle, fertilization and genetics of a child , The egg begins to actively share. The first 12 weeks of pregnancy are very important to the life and health of the child. At this time there is an active division of the oocyte maturation and the placenta - an organ, which is the 13th week of pregnancy completely take over the function to ensure the pregnancy hormones, metabolism Improves metabolism and losing weight without dieting   fetus and its protection against various harmful influences. And as during the first weeks of pregnancy, the child is not protected by the placenta, it is vulnerable to various influences: the mother of diseases, it has taken drugs, industrial and household hazards, and so on.

First divided cells only, while the embryo moves along the oviduct towards the uterus. At the end of the first week of the fertilized egg implants in the uterus, it is firmly attached to the mucosa.

Gradually, the embryo cells into three germ layers: ectoderm, endoderm and mesoderm. From the ectoderm later formed the shell of the fetus and placenta from the endoderm - the internal organs of the fetus. The mesoderm forms the final (at the end of the 3rd week of pregnancy) - it develops between the ectoderm and the endoderm. From this formed skin, skeleton, muscles of the fetus, the beginnings of his nervous system.

Since the beginning of the 4th week of pregnancy begins a new period in the development of the human embryo. Before that he shared a cell, they are now beginning to be shared and to acquire new properties, ie during the 4th week of pregnancy there is the main tab body tissues of the fetus.

At the beginning of the fifth week of pregnancy, the fetus reaches a length of 4 mm. He already has a head, bending the body, but there are no arms and legs. The head makes up a large part of the length of the body. The body is covered by skin, the muscles gradually develop, formed respiratory system and blood circulation. In an embryo already has a heart, but it has double chamber and not the quad, so the blood circulation is not in full force. Laid the digestive organs, kidneys and urinary tract, endocrine glands. In the second week of fetal development in a place fit the embryo to the uterine wall begins to form the placenta. At the end of the seventh week, the embryo becomes a four-chambered heart, gradually improving proper blood circulation. In the eighth week of pregnancy, the main organs of the embryo are already functioning.

In the ninth week of pregnancy, the embryo is called a fetus has, this week is an active maturation of the brain, increasing its volume and cell differentiation. The placenta grows in size, sprouting blood vessels, but is not fully operational.

12th week - it's the end of the first trimester, by which time the fetus reaches a length of 9 cm, weight - 20 g Almost half the length of the fetus head, all body parts well differentiated. His skeletal system there are points of ossification. By the end of the 12th week of fetal organs is almost completely formed. Good work cardiovascular and urinary system, the liver produces bile, which enters the intestine and promotes the recycling of food (because a child swallows amniotic fluid), developed genitals. The baby's face becomes more and more like a person's face: it has eyes, covered with lids, nose, mouth, lips, ears.

II trimester of pregnancy, with the 13th to 24th week - the most peaceful period of development

This is the most quiet and comfortable for the baby period. From the 13th week, the placenta begins to function, so the child becomes more secure: the placenta from the mother to him almost do not penetrate any harmful substances. Baby continues to grow, its growth reaches 10 cm or more, weight - '25

From 21 to 24 week fetus reaches a length of 32 cm, weight - up to 650 g Fruit overgrown Zhirkov - he is actively deposited under the skin. If a child is born during this period, he has a chance to survive, but only if it will be created special conditions - the content of incubator (crib - incubator with constant temperature), intensive care and resuscitation.

III trimester of pregnancy, from the 25th to 40 week - our baby is preparing to enter into the light

During this period, continue to mature all organs and systems of the baby, it is growing and gaining weight. At 32 weeks, his skin becomes smoother (subcutaneous fat layer increases), but it is still red. At the birth of their children in the incubators also provide an occasion intensive care. Suckling the child is still missing in the case of the birth of this term it is fed through a tube.

In 36 weeks (length 46 cm, weight - up to 2500 g) the child becomes more rounded shape, wrinkled countenance disappears, lengthen the hair on the head, sealed cartilage on the ears. Most infants at this time already have a sucking reflex and a loud cry. After birth, these children are usually normally adapt to the new conditions, but some of them have observed inhibition of metabolic processes, which can lead to rapid weight loss in the first weeks after birth.

At 40 weeks the fetus matures (length - 50 cm, weight - more than 3200 g). The lower limit of the length of a full-term fetus - 47 cm, weight - 2500 He was quite able to transfer labor and adapt to adult survival. After the birth, he shouts loudly, opens his eyes, moving arms and legs, well suckles. And he was very happy to meet my mother.

Pregnancy lasts forty weeks. This is the time when a woman is resting and preparing to become a mother. During pregnancy there are different periods - a nice well-being and high spirits, melancholy, depression Depression - a little more than a bad mood , Ailments and so on. And, nevertheless, it is the perfect time. But here come the last days of pregnancy, a little more - and your baby will be born.

Hormonal "revolution" before delivery

In the last days of pregnancy under the influence of hormones is changing the operation of all organs and systems of a woman. This is necessary for the formation of the body's biological readiness for the expulsion of the fetus - it is this willingness to contribute to the fact that births occur time and proceed correctly.

It is known that during pregnancy the main hormone that ensures proper course of pregnancy, progesterone has been Progesterone - norm and pathology . Progesterone restrained contraction of the muscles of the uterus and warned spontaneous miscarriage. In the last days of pregnancy, progesterone is losing its primacy in the body begins to produce more female hormones - estrogen. Under the influence of estrogen produced contractile protein actomyosin, softens the cervix and increases the sensitivity of the muscles of the uterus to the active substance that can cause reductions (for example, oxytocin and prostaglandins). An increasing number of prostaglandins - biologically active substances that stimulate the contraction of the muscles of the uterus. It increases the level of hormones that prepare women to future stress How to beat stress? Create an oasis That is, to leave.

Placenta actively accumulates bioactive substances (enzymes, vitamins, minerals) capable of providing a high level of energy and plastic processes. The placenta also stops to suppress the production of substances that increase uterine activity, such as oxytocin and acetylcholine.

The physical condition of the woman in the last days of pregnancy

At the 9th month of pregnancy in women or increasing shortness of breath occurs due to the fact that most of the uterus backs organs of the chest cavity. In the last weeks before delivery shortness of breath usually takes as little stomach drops. This is the result of what the presenting part of the baby down in a small basin.

This increases the pressure on the bladder, causing a woman can be confusing for frequent urge to urinate. But may decrease phenomena such as heartburn and nausea. Constipation and flatulence usually concerned up to the birth.

There are signs of disturbances of the central nervous system and circulatory system: dizziness, fainting, insomnia, increased bleeding (eg, gums). Due to the compression of blood vessels, there are signs of varicose veins, which may be accompanied by swelling of the feet Swelling of the legs - do not leave without attention   and painful spasms of the leg muscles. One of the signs of stagnation in the veins - hemorrhoids, he is also concerned about pregnant women. There are back pain, muscle contractions of the uterus, which some women take over the fight.

How does the uterus before delivery

By the end of pregnancy in the uterus increases the number and size of muscle fibers and nerve endings (receptors). Therefore, the uterus becomes very sensitive with respect to the movements of the child. But in the last weeks of pregnancy, the number of nerve endings decreases: the body prepares the uterus for childbirth and tries to make them less painful. In contrast, the number of blood vessels in the uterus increases up to the birth.

The cervix is ​​the last days of pregnancy under the influence of estrogen becomes more soft, ready for disclosure. At this time, in the cervical canal increases mucus production, which forms the channel protective tube neck without allowing infection to penetrate into the uterine cavity. With the onset of labor, this protective tube extends in the form of mucous secretion.

Condition of the fetus before birth

Before birth the baby becomes less active, it is not so often moves. This is due to the fact that he grew up, and he left very little room for movement. This is normal. Usually, the fruit had already takes the desired position (head looking down and spin to the left). At this time, growing rapidly all the organs and tissues of the child matures brain. Of particular importance is the maturation of the lung tissue, since the lungs mature accumulate a sufficient amount of a substance that prevents law decay of the lungs (surfactant).

A woman should know that a child at that time already developed senses, so he hears it and understands the mother, father and other people. Not a word, of course, but emotional conversation he picks up very well (most likely, this is due to the heartbeat of the mother). So do not swear, it is better to speak softly to the child, including a peaceful and beautiful music.

If during pregnancy the baby is completely dependent on the mother's body, by the end of pregnancy, many of the processes taking place in his body on their own. That is, the child is ready to go into the light.

If a woman during pregnancy was observed in female consultation and follow all prescription, then very soon it will get a healthy baby.

Galina Romanenko