GC: n

S: Yale – http://www.yale.edu/ynhti/curriculum/units/1982/7/82.07.08.x.html (last access: 16 May 2016); NCBI – http://www.ncbi.nlm.nih.gov/pubmed/12858480 (last access: 16 May 2016).

N: 1. late 14c., “the young while in the womb or egg” (tending to mean vaguely the embryo in the later stage of development), from Latin fetus (often, incorrectly, foetus) “the bearing or hatching of young, a bringing forth,” from Latin base *fe- “to generate, bear,” also “to suck, suckle” (see fecund).
In Latin, fetus sometimes was transferred figuratively to the newborn creature itself, or used in a sense of “offspring, brood” (as in Horace’s “Germania quos horrida parturit Fetus”), but this was not the basic meaning. It also was used of plants, in the sense of “fruit, produce, shoot,” and figuratively as “growth, production.” The spelling foetus is sometimes attempted as a learned Latinism, but it is not historic.
2. The developing young in the uterus, specifically the unborn offspring in the postembryonic period, which in humans is from the third month after fertilization until birth. See also embryo. 
The stages of growth of the fetus are fairly well defined. At the end of the first month it has grown beyond microscopic size. After 2 months it is a little over 2.5 cm long, its face is formed, and its limbs are partly formed. By the end of the third month it is 8 cm long and weighs about 30 g; its limbs, fingers, toes, and ears are fully formed, and its sex can be distinguished.
After 4 months the fetus is about 20 cm long and weighs over 200 g. The mother can feel its movements, and usually the health care provider can hear its heartbeat. The eyebrows and eyelashes are formed, and the skin is pink and covered with fine hair called lanugo. By the fifth month the fetus’s body is covered with a cheeselike substance (vernix caseosa), which serves to protect it in its watery environment. By the end of the fifth month it is 30 cm long, weighs 450 g, and has hair on its head. At the end of the sixth month it is 35 cm long and weighs 900 g, and its skin is very wrinkled.
After 7 months the fetus is 40 cm long and weighs over 1.3 kg, with more fat under its skin. In the male, the testes have descended into the scrotum. By the end of the eighth month it is 45 cm long, may weigh 2.3 kg, and has a good chance of survival if it is born at that time. At the end of 9 months, the average length of a fetus is 50 cm and the average weight is 3.2 kg. adj., adj fe´tal.
3. Basically, a baby is referred to as an embryo till 8 weeks after conception. After this time, he or she will be known as a fetus till he is born.

S: 1. OED – http://www.etymonline.com/index.php?term=fetus (last access: 16 May 2016). 2. TFD – http://medical-dictionary.thefreedictionary.com/Fetus (last access: 16 May 2016). 3. DB – http://www.differencebetween.net/science/difference-between-embryo-and-fetus/ (last access: 16 May 2016).


CR: Cesarean section, embryo, midwife, pregnancy.