Prenatal development of the child: Week by Week
- -natal development of the child: week after week
- By trimester
-natal development of the child - a very difficult, but interesting process.In total for the first nine months of the fertilized ovum is formed little man.In the first week laid all the major organs and systems, and then during pregnancy, they are improved.
Pregnancy lasts forty weeks, that is nine calendar months, and in the moon - ten.
For ease of calculation of gestational age is calculated according to the lunar calendar, that is, one month equals four weeks.
first month of pregnancy
After the merger in the oviduct the egg and sperm begins a new life.After some time, the embryo begins to divide, and about the third or fourth day the fertilized egg becomes like a mulberry.This formation is composed of eight to twelve large cells that are close to each other is called a morula.
embryo continues to divide and gradually moving into the uterus.By the middle of the sixth or early seventh day formed blastula (bubble).It is as follows: morula cells are divided into embryonic knot and a layer of superficial cells, with a cavity in the bud.
After entering the uterus fertilized egg attaches to the wall and it is gradually sinking into the mucous membrane of the body.This process is called implantation and continues for about forty hours.Outside the bubble cells grow into the mucosa and there begins to branch.Inside the small blood vessels are formed, which will nourish the baby before birth.All these processes take place in the first week of pregnancy.
During the second week begin to develop extraembryonic parts, amniotic bubble, the placenta and the umbilical cord.Amniotic bubble - a closed bag, inside of which will be the fruit with the amniotic fluid.
In the surface layer portion of the cells that grow into the uterus, the placenta begins to form.With this important body in the future will be the power of the fetus, its supply of oxygen and removal of metabolic products Metabolism: The basis of life of all living .It prevents the placenta into the baby's body of harmful substances and microbes.The formation of the placenta is to the sixteenth week of pregnancy.
child's body is connected to the placenta by the umbilical cord.In her vein and two arteries blood flows from the placenta to the fetus and back.
At the same time, the cells of the embryonic node are separated into two layers.They adopt disk-shape.
the third week between the layers of the disc is formed another, medium, paper.The last chord is formed - the future backbone.Also, the average leaf will give rise to muscle, bone, cartilage, internal organs, blood vessels and the heart, blood, lymph, gonads and shells that line all the cavities of the human body.
From the outer layer of skin is formed, the coating tissue dental epithelium of the ears, eyes and nose, hair and nails.From it also develops future nervous system.The cells of the inner layer forms the epithelium of the respiratory and digestive systems, liver and pancreas Diabetes and pancreas - the things you need to know .
Approximately twentieth day embryo segregated from extraembryonic parts.It appears the front (the future head) and rear ends (the pelvis and lower limbs).In three weeks the fetus already has the rudiments:
- digestive system: intestinal tube, and pancreas;
- two bronchi and trachea;
- Kidney as pronephros;
- Hearts in the form of the heart tube;
- circulatory system;
- nervous system.
On the fourth week, the embryo is formed from the germ of the umbilical cord slips through which he will be able to float freely in the amniotic fluid.
During this period, the embryo resembles a fish embryo.At the twenty-third day of the heart begins to contract.On the sides of the body limb buds appear as small buds.The unborn child has a cylindrical shape with a large head end.
In the fifth week, already have the beginnings of the lungs, the kidneys are laid, increasing the intestines.The liver begins to work actively and takes over the function of hematopoiesis.The heart begins to function as well as in adults.Formed face and limb buds.The nervous system continues to improve.
child's eyes, which were previously located on the sides of the head, begin to converge on the sixth week.Limbs begin to divide into sections: shoulder, forearm, wrist, and so on.Appears nose and ears beginnings.
the seventh week there are grains of teeth, skeletal ossification centers are formed.After another seven days develops muscle tissue, which can already be reduced, become discernible fingers.On the fiftieth day of the baby brain waves are recorded.The brain at this time has the departments, and the cerebral cortex is divided into layers.
From that time until the next birth the baby is called a fetus.His face takes on human form.Formed placenta, liver continues to evolve.
on the fingers and toes appear rudiments of nails.By the twelfth week of the child already has a "prints" the fingers.Begin to work the muscles, and the fruit makes its first movement (moving arms and legs, turns its head and opens its mouth), he first tries to suck and swallow.At the same time it begins to develop voice-machine.
intestine lengthens, curls in a loop, and begins the process of digestion.At the end of the third month begin to form sexual organs, but at this stage to distinguish boys from girls is almost impossible.
intensive development pathways of the nervous system.As a result, the fetus appears skin sensitivity, it can in response to stimulation compress a fist.
At this time, the baby is growing very rapidly.Actively developing skeleton and digestive system of the fetus.Begin to work the stomach, gall bladder and intestines.In the latter there is meconium - original feces, which consists mainly of bile.By the end of the sixteenth week of possible sex determination.
hematopoiesis begins to perform the red bone marrow, and the liver becomes an organ of digestion.The kidneys secrete urine, by which amniotic fluid is constantly replenished.
Fetal movements become more active, and the woman at repeated pregnancies can already feel them.The child is a mouth cam and sucks his thumb.He swallows amniotic fluid and thus provides the digestive and excretory systems.
arise and gyri of the cerebral cortex.Adrenal glands begin to work and thymus - endocrine organs.
baby's skin is very delicate, transparent and forms folds.Due to the fact that blood vessels are visible, it is appears red.
Subcutaneous fat thickens, and the vessels become less visible.On the head and body of the child appear vellus hair, the fruit is covered syrovidnoy (vernix) with grease.This substance is formed from the secretions of the sebaceous glands and accumulates in large amounts in the folds of the feet and hands, axillary and inguinal folds, behind the ears, on the face and scalp.Syrovidnaya lubricant protects the skin from harmful micro-organisms and mechanical damage.
nulliparous women feel the first movement of the fetus during this period.Of the blood becomes spleen.
gradually begins to work almost the entire endocrine system: pituitary, pineal, thyroid, parathyroid and pancreas, adrenal glands.These hormones play an important role in the development of the fetus.Formed vestibular apparatus.
baby's face appears facial expressions.He can smile, blink and lower corners of her mouth.
Although the baby's skin remains wrinkled beneath it appear fat.At this time, his eyes have already been formed, appearing eyelashes and eyebrows.The whole body of the fetus is covered with grease and syrovidnoy vellus hair.
child begins to make permanent respiratory movements.The lungs were not disclosed, but they gets a little amniotic fluid.It absorbs quickly and does not cause harm to the child.
All departments of the digestive system (esophagus, stomach, intestines, pancreas and liver) are already well formed.It ends with the formation of the brain.
fruit moves freely in the amniotic fluid, his movements become more energetic.Periods of activity followed by periods of sleep Dreams: how to understand our dreams , the total duration of from sixteen to twenty hours a day.The child at this stage of pregnancy respond to bright light and loud sounds.
skin retains the color red, and because of the abundance of wrinkles fruit still has the old look.The cartilage of the nose and ears are soft, and the nails do not reach the edges of the fingers.Movement messy baby in the uterus still has free space, and the child is free to move in it.
formed in the lungs alveoli (tiny bubbles) and alveolar ducts (pneumatic tubes).It begins to produce surfactant - a substance that helps the alveoli open during inspiration.
fetal brain receives information from our senses, and the child can distinguish between some tastes and smells good to hear, respond to bright light.
The endocrine system is more advanced in this regard, the fetus is formed by a special type of metabolism.
Growing fruit occupies almost the entire uterus, and his movements are not as chaotic.During this period, he was in the position in which to be born.Most of all, he is head down and back toward the left wall of the uterus.
heart shaped almost completely, but the circulatory system of the fetus has its own characteristics.Between the right and left atria there is a hole, which is closed at birth.Also, the child has arterial canal, which connects the aorta to the pulmonary artery.Normally after birth it stops working.Due to this particular anatomy of the fetus in the circulatory system circulates the mixture of arterial and venous blood.
rounded shapes the child's body, the skin is pink.Vellus hair start to disappear, reducing the amount of lubricant syrovidnoy.Nails a little favor fingertips.
fruit occupies almost the entire uterine cavity, and reduced physical activity.Ends tab of the alveoli, and each of them is covered with surfactant.Special center in the brain may already keep breathing.
liver and the pancreas continues to evolve, but the time of birth they have not yet fully formed.Continue to mature kidneys and other organs.A child can already distinguish the tone of voice, it responds to musical sounds.
almost disappear vellus hair syrovidnaya lubricant is only in the folds, genitals, behind the ears, on the scalp, on the sacrum and lower back.By the thirty-eighth week the fetus is considered to be a mature or full-term.
Many agencies already perform their functions.Formed sucking machine, on the mucous membrane of the lips and jaw in a newborn has special rollers that facilitate this process.The digestive tract becomes completely passable, and the intestines slowly promotes original feces into the lower parts.It ends with the formation of sex organs.
changes occur in the endocrine system.The adrenal glands increase in size.During labor they produce large amounts of adrenaline and noradrenaline - stress hormones How to beat stress?Create an oasis .In the blood of the newborn of these substances it contained much more than an adult during a very severe stress.These features help the child to be an active participant in the generic process.
fetal nervous system and sensory organs are also continuing to develop.The child responds to the emotional signals that come from the mother.
By the end of the tenth month of the fruit gives the body a woman momentum - a signal to start labor.At this time the child is ready to be born.