Pregnancy and Exercise
plays an important role in promoting health and well-being for pregnant women.
Women who exercise during pregnancy have reduced weight gain, more rapid weight
loss after pregnancy, improved mood and improved sleep patterns. Some studies
have also shown faster labors and less need for induction with pitocin in women
who exercise regularly during pregnancy. Others have demonstrated that women who
regularly exercise are less likely to require epidural analgesia and have fewer
Pregnancy is a highly complex physiologic state however, and precautions are
needed during pregnancy to ensure that your exercise program does not contribute
GUIDELINES FOR EXERCISE IN PREGNANCY
The following are simple guidelines to follow to ensure the safety and
well-being of you and your baby:
If you have been following a regular exercise program prior to your
pregnancy, you should be able to maintain that program to some degree
throughout your pregnancy. Exercise does not increase your risk for
If you are just starting an exercise program as a way of improving your
health during your pregnancy, you should start very slowly and be careful
not to over exert yourself.
Listen to your body. Your body will naturally give you signals that it
is time to reduce the level of exercise you perform.
Never exercise to the point of exhaustion or breathlessness. This is a
sign that your baby and your body cannot get the oxygen supply it needs.
Wear comfortable exercise footwear that gives strong ankle and arch
Take frequent breaks and drink plenty of fluids during exercise.
Avoid exercise in extremely hot weather.
Avoid rocky terrain or unstable ground when running or cycling. Your
joints are more lax in pregnancy and ankle sprains and other injuries may
Contact sports should be avoided during pregnancy.
Weight training should emphasize improving tone especially in the upper
body and abdominal area. Avoid lifting weights above your head and using
weights that strain the lower back muscles.
During the second and third trimesters, avoid exercise that involves
laying flat on your back as this decreases blood flow to your womb.
PHYSICAL CHANGES DURING PREGNANCY THAT MAY CHANGE EXERCISE ABILITIES
Include relaxation and stretching both before and after your exercise
Eat a healthy diet that includes plenty of fruits, vegetables and
Lungs and Breathing
In pregnancy the respiratory rate is naturally increased. Because of this,
the body works harder to give enough oxygen to the developing fetus. This can
reduce the amount of oxygen available for exercise and can cause decreased
endurance and a sense of breathlessness.
Because of the enlarging womb, the lower back develops more curvature and
the center of gravity for your body shifts. This can cause changes in your sense
of balance and requires adjustments in posture to prevent injury. Usually women
find that they naturally alter their exercise program to accommodate these
changes, especially in the last trimester of pregnancy.
The joints also undergo changes during pregnancy. Your body releases a hormone
called relaxin which loosens up the joints of the pelvis to make room for the
birth of your child. Because all of the joints in the body are more lax, there
is a greater chance of spraining or straining muscles and joints during
During pregnancy your body uses carbohydrates more quickly. Exercise also
increases the metabolism of carbohydrates. These two factors can lead to low
blood sugar reactions during exercise. Increasing caloric intake to shift your
carbohydrate balance is very important for pregnant athletes.
Your body increases its blood volume by 40% in pregnancy and your heart rate
increases by about 15 beats per minute. This allows nutrients and oxygen to be
transported to the fetus more efficiently. However, with the growth of the womb,
the flow of blood in the body can be disrupted and lightheadedness can occur.
EFFECTS OF EXERCISE THAT CAN AFFECT YOUR PREGNANCY
While exercising, blood flow shifts away from your internal organs so that
your muscles, lungs and heart get a larger share of oxygen. Extreme exercise can
cause too large of a shift of oxygen away from the uterus. That's why reducing
the length of time that you exercise strenuously and monitoring your heart rate
may prevent problems with your pregnancy.
During exercise the brain releases more norepinephrine, a neurotransmitter
that can reduce depression and influence blood flow to your heart and kidneys.
Norepinephrine also increases smooth muscle contraction and can cause increased
uterine activity in the form of painless contractions. These contractions have
not been shown to cause labor, but because of the possible influence on
contractions, women who have risks for pre-term labor should be on mild exercise
Elevated Body Temperature
Exercise causes an increase in core body temperature. Some studies have
shown that high fevers during the first three months of pregnancy can affect the
fetus's development while other studies have not confirmed these findings.
However, women who are extremely fit actually have improved body temperature
regulation and have decreased core body temperature during pregnancy. Because of
the conflicting data available, general guidelines would include caution when
exercising in very hot weather and attention to adequate fluid intake during
COMPLICATIONS OF PREGNANCY THAT MAY AFFECT EXERCISE ABILITY
Anemia, or a low blood count, results in lower oxygen carrying capacity of
your blood. This has a big impact on endurance and may result in a marked
decrease in your exercise capability because of breathlessness, dizziness and
fatigue. Women with anemia who want to continue their exercise program should
eat an iron-rich diet, take extra vitamin C with meals to increase iron
absorption and should take iron supplements if prescribed by their maternity
Some women experience pre-term contractions throughout their pregnancy.
While pre-term contractions do not always lead to pre-term birth, they do
increase a women's risk of pre-term labor significantly. If you have frequent
contractions during your pregnancy, strenuous exercise may lead to a higher rate
of contractions. Exercise programs should be adjusted to include more non-weight
bearing exercise like yoga, stretching and swimming rather than speed-walking or
Low Back Pain/Sciatica
Many women have episodes of low back pain or leg pain during pregnancy
because of weight changes and changes in body posture. Weight-bearing exercise
can increase pain levels and further stress the joints. Again, non-weight
bearing exercise may help with these symptoms. Swimming is particularly helpful.
CONTRAINDICATIONS TO EXERCISE DURING PREGNANCY
Toxemia/High Blood Pressure
Women who have high blood pressure can benefit from a regular exercise
program, however, women who develop high blood pressure in pregnancy should stop
their exercise program. Toxemia, or high blood pressure that develops during
pregnancy, is thought to involve a severe problem with blood vessels throughout
the body. Exercise can worsen toxemia and should not be continued.
Placenta Previa/Vaginal Bleeding
Placenta Previa is a condition where the placenta grows low in the uterus
and actually covers the opening to the cervix. It can cause severe bleeding
during pregnancy. Any women with placenta previa or with vaginal bleeding of an
unknown cause should not participate in an exercise program.
Preterm Labor or History of Preterm Labor
Women who have delivered a baby before 36 weeks of pregnancy should be very
cautious in participating in an exercise program during the second and third
trimesters of pregnancy. Stretching, yoga and walking are preferred forms of
exercise, while weight-bearing exercise should be avoided. Also, women with
pre-term contractions should avoid exercise that increases uterine contractions,
whether painful or painless.
Intrauterine Growth Retardation (IUGR)
IUGR is poor growth of the baby. This is diagnosed by your maternity care
provider by measuring the growth of your uterus and by checking a fetal
sonogram. If your baby has IUGR, it may mean that the baby is not getting an
adequate oxygen supply from the placenta. There are many causes of IUGR
including smoking, drug use, infections and poor blood flow to the placenta.
Because exercise shifts blood flow away from the placenta, a baby that is not
growing well will not tolerate exercise by it's mom.
Women who are pregnant with more than one fetus have a higher risk of
complications or pregnancy including pre-term labor. Exercise should be limited
to non-weight bearing and should focus on toning and stretching.
Exercise increases the strain on the heart, as does pregnancy because of
increased blood volume. Women with heart problems should exercise only under the
supervision of their cardiologist and maternity care provider.
Contributed by Mara V. Saulitis, M.D.
Family Practice and Obstetrics
Cherry Street Medical Group
500 Doyle Park Drive, Suite 200
Santa Rosa, CA 95405
Dated 13 August 2012