Plain Facts for Old and Young

by John Harvey Kellogg

At the fifth month, the fetus is nearly a foot long, and weighs about half a pound.

At the sixth month, the average length of the fetus is about thirteen inches, and its weight one and a half to two pounds. If born, life could continue a few minutes.

At the seventh month, the fetus is from fourteen to fifteen inches long, and weighs two to three pounds. It is now viable (may live if born).

At the eighth month, the length of the fetus is from fifteen to sixteen inches, and its weight from three to four pounds.

At the ninth month, the fetus is about seventeen inches long, and weighs from five to six pounds.

At birth, the infant weighs a little more than seven pounds, the usual range being from four to ten pounds, though these limits are sometimes exceeded.

[Duration of Gestation.]—The length of time required for the development of a human being is usually reckoned as about forty weeks. A more precise statement places it at about two hundred and seventy-eight days. This limit is often varied from. Cases have occurred in which a much longer time has been required, and numberless cases have occurred in which human beings have been born several weeks before the expiration of the usual time, as stated. There is some uncertainty respecting the exact length of the period of gestation, which grows out of the difficulty of determining, in many cases, the exact time when conception takes place.

[Uterine Life.]—The uterine life of the new individual begins with the impregnation of the ovum, which occurs the instant it is brought in contact with the zoösperms of the male. While in the uterus, the young life is supported wholly by the mother. She is obliged to provide not only for her own sustenance, but for the maintenance of her child. And she must not only eat for it, but breathe for it as well, since it requires a constant and adequate supply of oxygen before birth as much as afterward.

[How the Unborn Infant Breathes.]—Oxygen and nutriment are both supplied to it through the medium of an organ called the placenta, which is a spongy growth composed almost entirely of blood-vessels, and is developed upon the inner wall of the uterus, at the point at which the ovum attaches itself after fecundation. The growing fetus is connected with this vascular organ by means of a sort of cable, called the umbilical cord. The cord is almost entirely composed of blood-vessels which convey the blood of the fetus to the placenta and return it again. The fetal blood does not mix with that of the mother, but receives oxygen and nourishment from it by absorption through the thin walls which alone separate it from the mother's blood.