The development of our human baby is an extremely complex process, from embryo to mature fetus, the whole process takes about 40 weeks, so have you ever wondered what the fetal stages look like in the body?
So let's take a look at the development of the fetus from 4 weeks to 40 weeks.
4-week fetus.
First of all, in the fourth week of fetal development, that is, about a month, the fetus at this time is still a small embryo, just rooted in the mother's body, at this time the fetal body and head ratio is about 2:1, and you can see from the ** above, there is a long tail, the overall shape of the fetus at this time is like a small hippocampus.
At this stage, some important nervous system, blood and other circulatory organs such as the brain and spinal cord of the fetus are initially formed.
Fetus at 5 weeks.
By the time the baby reaches the fifth week of development, the brain and spinal cord begin to grow, and the baby is about 04cm，
And it will be firmly "rooted" in the mother's body, and gradually expand its territory around it.
At this stage, the fetus officially enters the embryonic stage, which is mainly composed of three germ layers, which will form the baby's organs and some tissues in the future.
And with the gradual development of the embryo, the amniotic cavity will expand accordingly.
During the fifth week, the most primitive cardiovascular system of the fetus will gradually appear, and the phenomenon of beating will appear.
7 weeks of fetus.
When the fetus reaches 7 weeks, the baby's appearance and facial organs, including the joints of the body, have changed greatly.
The 7th week of the fetus is a critical developmental node, and the fetus will make its first movement during the week, which is also the beginning of fetal movements.
We can see from the ** that the facial organs of the fetus can already be clearly distinguished, the black spots presented by the eyes, as well as the outline of the nose and the general shape of the ears.
At this stage, the fetus's heart can already divide the atria and ventricles, and it can beat about 120-150 times per minute.
8-week fetus.
At the 8th week, the fetus's complex organs begin to grow rapidly.
The baby's heart and brain have begun to develop, the eyelids have begun to crease, the nose has gradually erected, and the ears have continued to take shape.
Fetus at 12 weeks.
The 12th week is the middle stage of fetal development, at which the fetus can already see a distinct human shape, the head, limbs, various organs, and even the hands and feet have begun to move.
We can see the fetus's fingers through the breakthrough, as well as some blood vessels.
Fetus at 16 weeks.
When the fetus develops to 16 weeks, the fetus at this stage has entered a period of rapid development, the fetus's head, periphery, chest, abdomen, and internal organs have basically developed completely, and the fetus's head begins to gradually appear hair, some joints can also begin to move, and the sex of the fetus can be confirmed.
Fetus at 20 weeks.
At this stage, the fetal sensory system begins to develop rapidly, the fetus's sense of taste, hearing, and vision have entered a critical period of development, and the fetus at 20 weeks can already begin to swallow amniotic fluid and excrete it.
Fetus at 28 weeks.
At 28 weeks, the appearance of the fetus and the development of internal organs will be more perfect, the brain will enter the development period again, and the differentiation of brain cells will gradually form, close to the brain structure of **.
What is very interesting here is that the fetus can form its own sleep cycle and also begin to dream.
Fetus at 36 weeks.
At 36 weeks of pregnancy, the fetus weighs about 28 kg, already approaching or reaching its highest peak. At this stage, the fetus is about 45 cm long, and subcutaneous fat begins to appear on the body, the body becomes round, wrinkles are reduced, and the body is shiny. The bones of the fetus are also basically mature and quite hard.
The fetus's stomach and kidneys are more developed, secreting small amounts of digestive juices and beginning to urinate in the amniotic fluid. The baby's liver has also been able to dispose of some waste products.
In addition, one of the fetuses has completed the pelvic insertion, burying its head in the mother's pelvis, and its back facing the mother's womb, ready to meet the mother.
Fetus at 40 weeks.
In the last 40 weeks, the fetus has matured and will be born at this stage.