window open; on the contrary, breathing fresh air day and night is
one of the best ways to prevent colds.

OUTDOOR EXERCISE.--Outdoor exercise is indispensable to good health.
It benefits not only the muscles, but the whole body. By this means
the action of the heart is strengthened, and consequently all the
tissues receive a rich supply of oxygen. Exercise also promotes the
digestion and the assimilation of the food. It stimulates the sweat
glands to become more active; and, for that matter, the other
excretory organs as well. It invigorates the muscles, strengthens the
nerves, and clears the brain. There is, indeed, no part of the human
machine that does not run more smoothly if its owner exercises
systematically in the open air; and during normal pregnancy there is
no exception to this rule. Only in extremely rare cases--those,
namely, in which extraordinary precautions must be taken to prevent
miscarriage--will physicians prohibit outdoor recreation and,
perhaps, every other kind of exertion. Under such circumstances the
good effects that most persons secure from exercise should be sought
from the use of massage.

The amount of exercise which the prospective mother should take
cannot be stated precisely, but what can be definitely said is this--
she should stop the moment she begins to feel tired. Fatigue is only
one step short of exhaustion--and, since exhaustion must always be
carefully guarded against, the safest rule will be to leave off
exercising at a point where one still feels capable of doing more
without becoming tired. Women who have laborious household duties to
perform do not require as much exercise as those who lead sedentary
lives; but they do require just as much fresh air, and should make it
a rule to sit quietly out of doors two or three hours every day. It