Exercise in Pregnancy
An increasing number of adolescent females are participating in recreational and competitive sports, strength training and other fitness activities. During pregnancy they may want to remain physically active and continue some of these activities. Other adolescents who were previously sedentary may want to begin an exercise program as part of a healthy lifestyle.
Safety of exercise during pregnancy
Observational and interventional studies support the tolerance and safety of moderate exercise in healthy
The fetus is protected from potentially harmful effects of maternal exercise (e.g., hyperthermia, decreased
uterine blood flow and oxygen delivery, decreased carbohydrate availability and uterine contractions) by
maternal physiologic adaptations to pregnancy.
Exercise in normal (uncomplicated) pregnancies has not been associated with compromised fetal growth
and development, premature labor or delivery complications.
Mild to moderate exercise in pregnancy has been associated with a neutral or beneficial effect on pregnancy outcome.
Healthy, well-nourished adolescents without obstetrical or medical complications can safely exercise with few restrictions during pregnancy.
Adolescents who are trained athletes prior to pregnancy can continue to exercise throughout pregnancy
with modifications made as needed.
Adolescents who were not exercising regularly prior to becoming pregnant can safely begin an exercise
program during pregnancy.
Potential benefits of exercise during pregnancy
Physiologic considerations affecting exercise during pregnancy
- Fewer physical discomforts (e.g., fatigue, nausea, leg cramps, backache, constipation, round ligament pain, shortness of breath).
- Decreased incidence of operative delivery, gestational hypertension and preeclampsia.
- Improved blood glucose control in gestational diabetes.
- Shorter active phase of labor.
- Improved self esteem and body image.
- Decreased stress and anxiety and improved sleep.
- Less isolation from non pregnant peers.
- Increased placental weight, blood flow and infant birth weight.
- Maintenance or improvement of fitness level.
- Less likelihood of excessive weight gain.
- Fewer stretch marks.
- Improved posture.
- Faster postpartum recovery.
Physiologic changes associated with pregnancy may affect exercise tolerance and safety and must be considered when modifying or developing prenatal exercise programs.
Beginning early in pregnancy, relaxin softens and stretches connective tissue, resulting in laxity and
instability of ligaments and joints and increased risk of sprains and strains.
The enlarging uterus and breasts and growing fetus shift the center of gravity, resulting in balance problems, increased lumbar lordosis (sway back), and greater strain on the lower back and hips.
Weight gain may place additional stress on joints and make movement more difficult.
In later pregnancy, edema may limit range of motion and cause nerve compression.
Pressure exerted on the vena cava by the enlarging uterus may result in decreased cardiac output and
reduced blood flow to the uterus when exercising on the back after the first trimester. Symptoms may
include dizziness and shortness of breath.
Hypoglycemia can occur more readily, especially in later gestation, or with prolonged, strenuous exercise,
since carbohydrate utilization is greater in pregnancy.
Increased resting oxygen consumption lowers oxygen availability for aerobic exercise in pregnancy.
Guidelines for exercise during pregnancy
Prenatal exercise programs must be individualized according to the adolescentís health status, interests
and fitness level. Desirable components include aerobic conditioning, strength training and flexibility
Regular exercise (at least three times per week) is preferable to intermittent activity or a sudden increase
in exercise level, which can result in muscle strain.
Exercise sessions should begin with a warm-up and end with a cool-down and relaxation period (e.g., 10-
15 minutes of slow walking or stationary cycling on low resistance followed by gentle stretching). This will reduce the risk of ligament and back strain, ensure a safe cardiovascular response, normalize metabolic rate and respiration and prevent pooling of blood in exercising muscles. After exercise, the adolescent should rise gradually from the floor to prevent dizziness.
Exercises that require lying on the back should be avoided after the first trimester.
Exercise intensity should be light enough to allow conversation and prevent shortness of breath, fatigue, pain, and exhaustion. Since resting heart rate increases and maximum heart rate decreases in pregnancy, monitoring target heart rate to determine exercise intensity is of limited usefulness.
Fatigue and discomfort may be less likely if exercise intensity is decreased in later pregnancy (e.g., exercising more slowly with fewer repetitions, or engaging in less strenuous activities such as doubles tennis instead of singles, walking instead of running).
Exercise sessions should be short enough to prevent hypoglycemia, fatigue and discomfort (e.g., 20-30 minutes of moderate aerobic activity, 3-5 times per week).
Running may require shorter distances, slower speeds, flatter terrain and more frequent rest periods.
Strength training should be limited to 2-3 times per week using light weights (2-5 kg) and fewer repetitions. Heavy free weights or heavy resistance on weight machines could increase the risk of spinal disc injury and intra-abdominal pressure. Straining and breath-holding should be avoided.
Exercise activities that do not require a high degree of balance and coordination, quick movements, or
involve the risk of falling or fetal trauma are considered safe during pregnancy.
The pelvic tilt will help strengthen abdominal muscles, and decrease round ligament pain and lumbar lordosis. Instruct the adolescent to stand, lie or sit with feet hip-distance apart and knees slightly bent,
while the muscles of the abdomen and buttocks are contracted. The pelvis is thrust forward and the pelvic
bone is rolled upward.
Exercises which strain the lower back, stress ligaments, cause knee trauma or promote separation of
the of the symphysis pubis (junction of pubic bone) should be avoided. These include full sit-ups, sitting
cross-legged, double leg lifts, side leg swings, toe touches, squatting, deep knee bends and bridging
(lifting buttocks off floor from lying position).
Jerking motions, hopping, jumping, twisting or sudden changes in direction are contraindicated. Joints
should not be extended beyond the normal range of motion.
Water skiing could result in forceful entry of water into the uterus, which could result in miscarriage.
Scuba-diving may be associated with decompression disease, gas embolism, and in the first trimester, risk
of fetal malformation.
Particularly during the first trimester, overheating (which may have teratogenic effects on the fetus)
should be avoided. Exercise should not be done while febrile or in hot, humid weather. Saunas or hot tubs
may also increase the risk of hyperthermia and should be avoided. Exercising in light clothing during a
cooler time of day outdoors, or with a fan indoors will help prevent dehydration and hyperthermia in hot
A tightly carpeted or wooden floor will reduce the risk of slipping.
Walking or running on a cushioned track or grass will increase comfort and reduce the risk of injury.
Well-cushioned shoes that provide good support will aid balance and increase comfort.
Ample fluid intake is essential to prevent dehydration, which occurs more readily in pregnancy (10-12
cups per day, including 2 cups before exercise, 1 cup every 15 minutes during, and 2-3 cups after exercise).
Thirst may be depressed during exercise and cannot be relied upon to assure an adequate fluid
intake. Clear, light-colored urine is an indicator of adequate hydration.
An increased intake of carbohydrate will reduce the risk of hypoglycemia. Complex carbohydrates (e.g.,
bread, pasta, cereal) or milk, fruit or fruit juice should be consumed 1-2 hours before, and within 1 hour
Energy intake should be adequate to support exercise and promote optimal weight gain and fetal growth.
Weight loss should not occur with exercise during pregnancy. The energy required for weight-bearing
exercise (e.g., walking, running) increases with gestational weight gain.
The adolescent should be cautioned to stop exercising and contact her health care provider if any of the following occur:
Contraindications To Exercise
- Muscle weakness
- Shortness of breath
- Chest pain or tightness
- Vaginal bleeding or fluid loss
- Uterine contractions
- Abdominal pain
- Absent fetal movement
Adolescents with any of the following conditions should be advised not to exercise during pregnancy:
- Pregnancy-induced hypertension
- Preterm rupture of membranes
- Preterm labor (current or previous)
- Incompetent cervix/cerclage
- Persistent second or third trimester bleeding
- Intrauterine growth retardation
- Severe anemia
- Placenta previa
Adolescents with chronic hypertension or active thyroid, cardiac, vascular or pulmonary disease should
be evaluated individually to determine if exercise is advisable.
Postpartum Exercise Considerations
Musculoskeletal and cardiovascular changes associated with pregnancy gradually reverse during the
postpartum period and continue to affect the safety and comfort of exercise.
Ligaments and joints remain softened and at increased risk of injury for up to 12 weeks after delivery.
Cardiovascular changes may continue to affect exercise tolerance for 4-6 weeks postpartum.
The adolescent should be advised to gradually return to her pre pregnancy exercise level as tolerated.