Fetus is an organism from the ninth week of fetal development until birth. From the outset, the fetus has a ldquo;humanrdquo; shape, and on the 12th

Development of the human fetus by weeks [Formation]

Fetus is an organism from the ninth week of fetal development until birth.

From the outset, the fetus has a “human” shape, and on the 12th week — this is a “little human”. By the 9th week fetus reaches a length of 3-3.5 cm and a weight of 4 g. His heart has four chambers and contracts with a frequency of 130-150 beats per minute. His liver — the main organ of blood formation — fully forms by 20th week.

From the 12th week gradually occurs skeletal ossification, the muscles begin to function. By the end of the third month the fetus already has a length of 8-10 cm and its weight — 40 g; his head is 1/3 of the body length.

From the 18-20th week the fetus begins to move, and mother feels his weak pushes. The fetus already flexes his fingers, opens his mouth, turns the head, and even tries to suck his thumb.

Before 20 weeks the fetus auditory organ fully forms, and he can respond to sounds (such as music) with different movements. From the 28th week, when the fetus already has well-developed brain, he is able to respond not only to the power of sound, but also on its “quality”: he likes gentle treatment to him, quiet melodic music. Taken from http://worldofschool.org

Beginning with the fourth month of fetal development the formation of the bronchi and lungs completes, and with the sixth month there already observe chest movements that resemble breathing ones. At the end of the eighth month of pregnancy, the fetal weight is 1500-1600 grams and length is 40 cm. He begins to prepare for childbirth — turns his head down. By the ninth month his mass reaches 3200-3800 g, and the length is 50-54 cm. Such fetus may already exist outside the mother's body.

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