an individual in the third of the three stages of prenatal development (from about the 9th week until birth); a time during which the individual develops enough sophistication to be able to survive outside the mother's uterus
– The product of conception from the time of implantation until delivery If the delivered or expelled fetus is viable, it is designated an infant [45 CFR 46 203(c)] The term "fetus" generally refers to later phases of development; the term "embryo" is usually used for earlier phases of development (See also: Embryo )
The young or embryo of an animal in the womb, or in the egg; often restricted to the later stages in the development of viviparous and oviparous animals, embryo being applied to the earlier stages
see foetus. the usual American spelling of foetus. Unborn young of any vertebrate, particularly mammals, after it has acquired its basic form. In humans, this stage begins about eight weeks after conception (see embryo). The fetal stage, marked by increased growth and full development of the organ systems, climaxes in birth (see pregnancy, parturition). By the end of the third month, the arms and legs of the human fetus begin to move and reflexive movements (such as sucking) begin. Four months after conception, the fetus is about 5.3 in. (135 mm) long and weighs about 6 oz (170 g). During the fifth month, downy hairs (lanugo) cover the body and the skin becomes less transparent. At seven months, a protective greasy substance (vernix caseosa) covers the reddish, wrinkled skin. Fat is deposited under the skin during the eighth month, when the fetus typically weighs about 5 lbs (2.2 kg). A full-term fetus is about 266 days old
In medicine, this term is applied to the young of mammals when fully developed in the womb In human beings, this stage is reached after about 3 months of pregnancy Prior to this, the developing mammal is at the embryo stage