toward the eighteenth week of pregnancy; and in consequence twenty-
two weeks generally elapse between quickening and the day of
delivery. Although such a calculation is far from certain in its
prediction, there are instances in which no other calculation can be
made. A nursing mother, for example, may become pregnant before
menstruation has been reestablished. Under these circumstances,
obviously, the date of confinement cannot be estimated in the
ordinary way, and it is then especially important to know the first
day on which the fetal movements were felt. Furthermore, it is
helpful to note this date in every case, since it serves, if for
nothing more, to confirm the prediction made from the menstrual
record. Besides the two methods just described, which are alike in
that they require the patient herself to make the necessary
observations, there is a third method of estimating how far pregnancy
has advanced, by which the physician is enabled to draw his own
conclusions. This method is based upon the fact that the womb
enlarges from month to month during pregnancy at a constant rate. Up
to the end of the third lunar month it cannot be felt through the
abdominal wall; but in the course of the fourth month, on account of
its size, it must rise into the abdominal cavity. At the beginning of
the sixth month the top of the womb is at the level of the navel, and
at the ninth reaches the ribs. The diaphragm then prevents the womb
from going higher; and two or three weeks before the end of pregnancy
it drops several inches, causing a change in the figure which is
noticeable to the patient, since her skirts hang somewhat lower than
before. From this time on she is more comfortable, because the lungs
are not crowded, and there is less interference with breathing.

These alterations in the position of the womb indicate very
satisfactorily the month to which pregnancy has advanced, but not the