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Embryonic development in the human, covers the first eight weeks of development; at the beginning of the ninth week the embryo is termed a fetus. The eight weeks have 23 stages. Human embryology is the study of this development during the first eight weeks after fertilization. The normal period of gestation (pregnancy) is about nine months or ...
Gestational age: 3 weeks and 0 days until 3 weeks and 6 days old. 22–28 days from last menstruation. Embryonic age: Week nr 2. 1 week old. 8–14 days from fertilization. Trophoblast cells surrounding the embryonic cells proliferate and invade deeper into the uterine lining. They will eventually form the placenta and embryonic membranes.
At this stage, a fetus is about 30 mm (1.2 inches) in length, the heartbeat is seen via ultrasound, and the fetus makes involuntary motions. [47] During continued fetal development, the early body systems, and structures that were established in the embryonic stage continue to develop. Sex organs begin to appear during the third month of gestation.
A fetus is a stage in the human development considered to begin nine weeks after fertilization. [4] [5] In biological terms, however, prenatal development is a continuum, with many defining features distinguishing an embryo from a fetus. A fetus is also characterized by the presence of all the major body organs, though they will not yet be ...
In human pregnancy, prenatal development is also called antenatal development. The development of the human embryo follows fertilization, and continues as fetal development. By the end of the tenth week of gestational age, the embryo has acquired its basic form and is referred to as a fetus. The next period is that of fetal development where ...
Ensoulment. In religion and philosophy, ensoulment is the moment at which a human or other being gains a soul. Some belief systems maintain that a soul is newly created within a developing child and others, especially in religions that believe in reincarnation, that the soul is pre-existing and added at a particular stage of development.
There is no sharp limit of development, age, or weight at which a fetus automatically becomes viable. [21] According to data from 2003 to 2005, survival rates are 20–35% for babies born at 23 weeks of gestation (5 + 3 ⁄ 4 months); 50–70% at 24–25 weeks (6 – 6 + 1 ⁄ 4 months); and >90% at 26–27 weeks (6 + 1 ⁄ 2 – 6 + 3 ⁄ 4 ...
Mother with newborn baby. The postpartum (or postnatal) period begins after childbirth and is typically considered to last for six weeks. [1] There are three distinct phases of the postnatal period; the acute phase, lasting for six to twelve hours after birth; the subacute phase, lasting six weeks; and the delayed phase, lasting up to six months.