There is a third positive sign of pregnancy to which the physician
has recourse, but generally it is inapplicable as early as those
already mentioned. In the latter months of pregnancy it is possible
to outline the child through the mother's abdominal wall. Although
this procedure adds little or nothing to our resources for making an
early diagnosis, the information it ultimately affords proves one of
the greatest aids in the practice of obstetrics.

THE PROBABLE SIGNS.--Obviously, phenomena for which the child is
responsible--such as have just been described--supply the most
trustworthy evidence of pregnancy; and these phenomena alone are
accepted as positive signs. But there are earlier manifestations
which intimate very strongly that conception has taken place. Shortly
after pregnancy has become established changes begin in the uterus,
as physicians call the womb, and soon reach the point where they may
be recognized by a simple examination which enables the physician to
express an opinion little less than positive. As one result of
pregnancy, for example, the supply of blood is increased to all the
organs concerned with the reproductive process. Partly on account of
this congestion and partly on account of embryonic development, the
uterus becomes altered in a number of ways. Although these changes
occur regularly in pregnancy, they may also occur when the womb is
enlarged from other causes; therefore, if a physician should make the
diagnosis of pregnancy whenever they were found, he would make it
somewhat too frequently. With a little patience, however, he excludes
the chance of being misled; a second examination, approximately four
weeks after the first, will generally place the existence of
pregnancy beyond question, for under normal conditions the degree of
enlargement which takes place in a pregnant womb during a given
interval is absolutely characteristic.