Vigorous
Aerobic Exercise, Overheating,
and Birth Defects:
Fact vs. Fiction
Scientific
evidence has demonstrated a
link between maternal high-fever
and an increase in neural tube-related
birth defects, especially in
the first trimester of pregnancy.
Since the fetus cannot disperse
excess heat, medical professionals
once speculated that the increased
heat generated during vigorous
aerobic exercise might cause
birth defects similar to those
associated with the mother’s
high fever.
Contrary to speculation, the
slight elevation in maternal
core-temperature that occurs
during strenuous exercise presents
no threat to the developing
fetus. In fact, medical studies
have consistently observed several
maternal adaptations that aid
in regulating body heat and
that are strongly fetal protective
in nature.
How
Maternal Body Adaptations Protect
the Fetus
|
•
|
You’ll
notice that during exercise,
you will begin sweating
at lower levels of exertion
than you did when you weren’t
pregnant; this amplifies
cooling.
|
|
•
|
As your
body expands to accommodate
the developing fetus, so
does the surface evaporation
area of your skin. Relaxation
of blood vessels due to
pregnancy hormones increase
circulation to the body’s
surface areas; thus facilitating
efficient cooling. |
| •
|
When exercising during
pregnancy, your respiration
rate—how many breaths
you take per minute—speeds
up and your tidal volume—the
amount of air you take in
per breath—increases,
thereby raising the amount
of heat dissipated during
exhalation. |
PREGNANT
WOMEN SHOULD NEVER USE A HOT
TUB, SAUNA, STEAM ROOM, OR NATURAL
HOT SPRING AS THESE MAY RAISE
CORE TEMPERATURE TO DANGEROUS
LEVELS.
Stay Safe and Comfortable When
Exercising during Pregnancy
|
•
|
Stay
well hydrated during your
workout; see the Hydration
and Exercise during Pregnancy
web page for more information.
|
|
•
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For good
air-circulation and evaporation,
wear loose, comfortable
clothing, constructed of
loosely woven fibers or
specially patented sports-fabrics
that “wick away”
moisture to enhance cooling. |
|
•
|
As your workout
progresses, cool your body
by removing layers of clothing
as necessary. |
•
|
Avoid exercising
out-of-doors when the weather
is hot and humid. |
•
|
Stay out
of the hot sun during your
workout. |
•
|
Exercise
indoors when the outside
air-quality is poor. |
•
|
Bikram
or other “hot”
yoga styles are not recommended
during pregnancy. |
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EXERCISE
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