Prenatal development
...of length. During this stage the head develops before the rest of the body, and arms and legs develop before the hands and feet. By the fourth week you could hear the heart pumping. By the fifth week, the heart and liver are extremely big. The head is straightened. Cranial bones still does not exist, which allows seeing the interior of the embryonic brain. From the six to the eight week, the gonads (reproductive organ) of genetically male embryos secrete the hormone testosterone, and this simulates the development of male sex organ. Otherwise the embryo develops into a female. By the end of the eight week, the embryo has fingers toes etc. The embryo is still only an inch long and weighs a tenth of one ounce. Fetal Stage Is the last and longest stage in the prenatal development, extending from the ninth week after conception until birth. By the ninth week, the eyes start to open and it could move its tongue. Within the tenth and eleventh week, the fetus is 3 to 31/2cm from head to toes. The fetus still has sufficient space and it is warm and comfortable in the amniotic liquid. The fetus already has fingerprints, the brain and the organs of the body are present. By the twelve week the fetus body is completely formed. Its organs already are working and can feel pain. Also this is the week were most of the abortions are carry out. By the sixteen week you could see its facial features. The arms are long enough so it could unite the one to the other. By the fifth month, the mother can feel its movement. By the seventh month, the baby is already using is senses which are sight, hearing, taste, touch and it can recognize the voice of its mother. Also in this month, the baby has a change of surviving outside the womb. At eight month, the skin becomes thickness; it has a fat layer store underneath her with the purpose of protecting and feeding the baby. The baby absorbed almost four liters of amniotic fluid per day. At nine months, the weight of the baby increases 200 grams per week. As it grows, its movement becomes less frequent. The amniotic liquid incre...