consequence of the expulsion of the child, the after-birth, the
amniotic fluid, and a varying amount of blood, there is necessarily a
loss of from ten to fifteen pounds. Later, as the maternal tissues,
whose growth has been stimulated during pregnancy, return to their
original condition, a further loss in weight takes place. It is not
unusual, however, for women to remain permanently better nourished
than before they became pregnant. Under ordinary conditions the food
of the prospective mother provides not only for her own wants but
also for those of the embryo. Between the two organisms there exists
a relation which resembles that existing between a house in course of
construction and the contractor who supplies the building material.
The mother furnishes what is needed to construct the "living
edifice," as Huxley called the growing embryo, but she is not
responsible for the lines of the building. The embryo is both
architect and mechanic, designing the structure and arranging the
"organic bricks" in their proper places. The work of construction
necessitates the expenditure of an appreciable amount of energy and
the creation of waste products that must be removed, lest they
accumulate and interfere with the growing structure. These waste
products leave the embryo by way of the umbilical cord and the
placenta and return thus into the mother's circulation; ultimately
they leave the mother through the same channels that carry off her
own waste. First and last, then, the nutrition of the mother and of
the child are so bound together that it has been impossible to study
them separately. Our knowledge of food requirements during pregnancy
has been obtained by measuring the food requirements of the mother
alone; and as nutrition during gestation is fundamentally the same as
nutrition at other times, it is necessary for us first to consider in
general the food needed by the human body.