Most of the ailments to which prospective mothers are liable are
merely the natural manifestations of pregnancy, exaggerated to such
an extent as to cause inconvenience and discomfort. In the early
months, for example, persistent nausea and vomiting may become the
source of great annoyance, and later the pressure of the womb against
neighboring structures may cause a variety of symptoms. It does not
follow, however, that any of these ailments will necessarily appear.
On the contrary, many women are more healthy during pregnancy than at
any other time.

Occasionally illness is charged to pregnancy with which in reality
pregnancy has nothing to do. While awaiting the birth of a child,
just as at other times, women may suffer from coughs or colds, from
aches or pains, from malaria, pneumonia, typhoid fever, or in fact
from any disease. It is evident that such complications are
accidental; and, though pregnancy confers no immunity against them,
it does not, on the other hand, render women more susceptible to all
kinds of ailment.

And yet there are diseases for which pregnancy is directly
responsible. These are, to a very large extent, preventable; and,
though they occur rarely, precautions for their prevention should be
taken in every case of pregnancy. By far the most important members
of this group are the toxemias of pregnancy. These, as will be
explained later, cause symptoms which the patient herself may
recognize, and her physician may often detect their presence still
earlier by alterations in the composition of the urine. For this
reason routine examination of the urine during pregnancy is a means
of prevention indispensable for safeguarding the health of the
prospective mother.