Shortly after conception the breasts become congested; in consequence they enlarge, become tender, and begin to show swollen veins beneath the skin. The most significant alteration, however, occurs in the cells which line the glands; these increase in size at first; and then, by a process of cell division, their number multiplies. After pregnancy has advanced six to eight weeks these cells begin to elaborate the thin, watery fluid called colostrum. Contrary to popular belief, the quantity of colostrum is not prophetic of the character of the milk; there is no ill-omen, to be sure, in a plentiful secretion, but a meager one is quite as likely to be followed by successful lactation. At present we are unable to predict by any means either the quantity or the quality of the milk which a prospective mother will produce. Some writers contend that influences which come into play during girlhood ultimately affect the capacity of the breast for making milk; for example, irregular habits in youth and the wearing of improper styles of clothing are said to be particularly detrimental influences. Of course, a healthful mode of life at the time when a girl is approaching maturity reacts favorably upon her development in every way, and naturally enough the breasts share this benefit; but the relation between unhygienic habits at about the time of puberty and a subsequent deficiency in lactation has been exaggerated by many writers. It is impracticable, certainly, to institute special measures to prepare the breasts for their function until the need of such measures is clearly evident. Throughout pregnancy clothing about the breasts should be loosely worn. If the nipples are not already prominent they should be drawn out; and about six or eight weeks before confinement is expected they should be given the treatment described in Chapter V. For the first day or so after the infant begins to nurse its efforts have a tendency to injure the skin which covers the nipple; and unless measures to render the nipple resistant have been previously adopted, nursing may cause the mother considerable discomfort. Moreover, it is extremely important throughout lactation to keep the skin covering the nipple free from abrasions, for if it cracks bacteria have thus an opportunity to enter the glands and set up an acute inflammation which may result in the formation of an abscess. This complication is to be avoided, not only because of the unpleasant symptoms which attend it, but also because for the time it brings the usefulness of the breast to an end. Fortunately an abscess seldom impairs the breast permanently.