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Fetal viability refers to a point in fetal development at which the fetus may survive outside the womb. The lower limit of viability is approximately 5 + 3 ⁄ 4 months gestational age and is usually later. [20] There is no sharp limit of development, age, or weight at which a fetus automatically becomes viable. [21]
Different terms are used to describe prenatal development, meaning development before birth. A term with the same meaning is the "antepartum" (from Latin ante "before" and parere "to give birth") Sometimes "antepartum" is however used to denote the period between the 24th/26th week of gestational age until birth, for example in antepartum ...
Nine-week-old human embryo from an ectopic pregnancy. Organogenesis is the development of the organs that begins during the third to eighth week, and continues until birth. Sometimes full development, as in the lungs, continues after birth. Different organs take part in the development of the many organ systems of the body.
That stage of fetal development when the life of the unborn child may be continued indefinitely outside the womb by natural or artificial life-support systems. The constitutionality of this statutory definition (V.A.M.S. (Mo.),188.015) was upheld in Planned Parenthood of Central Mo. v. Danforth, 428 U.S. 52,96 S.Ct 2831, 49 L.Ed.2d 788.
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 ...
Gestational age: 20 weeks old. Embryonic age: 18 weeks old. The fetus reaches a length of 20 cm (8 in). Lanugo covers the entire body. Eyebrows and eyelashes appear. Nails appear on fingers and toes. The fetus is more active with increased muscle development. "Quickening" usually occurs (the mother and others can feel the fetus moving).
Movements such as kicking continue, and the mother usually feels movement for the first time, an event called quickening, during the fifth month. [17] Around this time, limb movements become more complex, with flexing of the joints and ribs. This activity assists with proper joint development. [15]
The embryonic period varies from species to species. In human development, the term fetus is used instead of embryo after the ninth week after conception, [19] whereas in zebrafish, embryonic development is considered finished when a bone called the cleithrum becomes visible. [20]