ordinarily eaten will suffice also during the later months of
pregnancy. On the contrary, popular opinion holds that the
prospective mother "should eat for two." It is not unimportant to
point out the erroneous character of this superstition, because
overeating during pregnancy is much more likely to provoke discomfort
than insufficient nourishment.

In order to comprehend the nutritional needs of the prospective
mother, one must keep in mind the fact that our food always serves
two purposes. These are, as we have seen, to build or to repair
tissue and to furnish heat and energy. Since these needs of the body
during pregnancy--as at all other times--are best understood when
considered in their relation to the food-stuffs which supply them, we
shall take up these various ingredients separately.

Protein, which repairs tissue and also furnishes the substance from
which new tissue is made, is used more economically during pregnancy
than when the maternal functions are inactive. As a result of this
economy the same allowance of protein which is sufficient before
conception is sufficient also during pregnancy. This fact has been
put in the clearest light by extensive observations made upon
animals. Dogs which were not pregnant, for example, have been
carefully fed so that their food should contain just enough protein
to cover the needs of the body and keep their weight constant.
Subsequently, when these animals became pregnant precisely the same
amount of protein was fed to them. The result was that they gained in
weight, and at the same time the waste products of protein they threw
off were notably diminished. Such observations, of which there have
been a large number yielding concordant results, may be safely taken
to mean that an amount of protein previously satisfactory for the