Exercise during Pregnancy
Is there a role for exercise during pregnancy?
There used to be a time when exercise was discouraged and deemed unsafe for a women during her pregnancy. Today, many women who exercise prior to becoming pregnant want to remain active during their pregnancy both for their fitness as well as the health of their baby. Other women who previously did not exercise want to begin a program to improve their fitness level, safely manage their weight gain and help prevent medical conditions associated with pregnancy such as hypertension and gestational diabetes. There are however many safety concerns for the pregnant athlete both regarding the mother and the baby, and there are clear guidelines for safety of exercise during pregnancy.
What are the benefits of exercise during pregnancy?
Regular exercise during pregnancy has many benefits both physiological on the athlete’s body and psychological as well. From a physical standpoint many of the discomforts of pregnancy can be reduced such as chronic fatigue, varicose veins and leg swelling (peripheral edema). An exercising pregnant woman can have improvements in aerobic capacity, lower blood pressure and decreased blood sugar due to the body’s improved response to carbohydrate metabolism. The psychological benefits of pregnancy are demonstrated by improved self-esteem and measurable decreases in depression.
What are its effects on blood pressure?
High blood pressure can be a significant risk to both the mother and fetus. On the more serious end of the spectrum is preeclampsia, a condition of maternal hypertension, protein spillage in the urine (proteinuria) and swelling (edema). Multiple research studies have demonstrated a decreased risk of preeclampsia occurring in expecting mothers who regularly exercise.
What are its effects on gestational diabetes?
Gestational diabetes is another serious condition of pregnancy where the pregnant woman develops carbohydrate intolerance during her pregnancy when she did not have diabetes prior to becoming pregnant. It can lead to type II diabetes in the mother following her pregnancy as well as having serious potential complications for the child. Pregnant women with gestational diabetes who regularly exercise have a decreased level of blood glucose. While not yet definitively proven to do so, exercise may play a role in controlling this serious medical condition of pregnancy.
What are the formal recommendations regarding exercise for pregnant women?
Many of the major obstetric medical organizations from around the world have published guidelines on exercise and pregnancy. In them, they all state that both aerobic and strength-training exercise can be safe for a pregnant mother and is actually recommended when there are no medical contraindications to doing so. The American College of Obstetricians and Gynecologists formal recommendation states, “In the absence of either medical or obstetric complications, ≥30 minutes of moderate exercise a day on most, if not all, days of the week is recommended for pregnant women.” Women at low risk for an adverse outcome of their pregnancy should be encouraged to engage in an aerobic and strength-training program. Female athletes who participated in athletics and exercise programs prior to their pregnancy should continue to do so provided their pregnancy remains uncomplicated.
Women who were sedentary prior to their pregnancy may also safely begin an exercise program with supervision. Multiple research studies have demonstrated physiologic health benefits to exercise in pregnant women who did not do so previously. Improvements have been demonstrated in such parameters as exercise stamina, blood pressure, fat index and maximum heart rate. A supervised and structured exercise regimen provides little if any risk to the mom or the fetus.
What are the contraindications for exercise during pregnancy?
There are some contraindications to exercising during pregnancy. These include any disorders that decrease fetal blood flow or oxygenation. Absolute contraindications to exercising for a pregnant athlete include the following:
● Preterm premature rupture of the membranes
● Antepartum hemorrhage
● Placenta previa
● Persistent 2nd and 3rd trimester bleeding
● Preterm labor
● Incompetent cervix
● Significant maternal cardiac disease
● Restrictive lung disease
● Growth-restricted fetus
● Chronic placental abruption
● Multiple gestation (ie. twins or triplets)
Other relative contraindications require the endorsement of the pregnant female’s obstetrician. These may include the following:
● Extreme underweight or maternal eating disorder
● Maternal cardiac arrhythmia or other cardiac disorder
● Respiratory disorder
● Previous spontaneous abortion
● Severe anemia
● Poorly controlled maternal hypertension
● Poorly controlled maternal diabetes
● Seizure disorder
● Thyroid disorder
● Other significant medical conditions
What can be done to maintain safety during exercising when pregnant?
It is important to emphasize safety during exercise for the expecting mother. The uterus and fetus must be protected from trauma and direct injury during exercise. Therefore certain sports and activities should be avoided during pregnancy. Inexperienced pregnant females should only exercise within a carefully structured and supervised program. In the second half of pregnancy, there should be a transition to non-weight bearing activities such as swimming and biking. Deep-water diving should be avoided because of the risk of decompression sickness and nitrogen gas in the bloodstream on ascent. There is a higher rate of spontaneous abortion in dives beyond 15 m. Collision sports like basketball, hockey and rugby to name a few should also be avoided to decrease the risk of a direct blow occurring to the fetus. During resistance training, the supine position should be avoided to maintain uterine blood flow. Lighter weights should be used as pregnancy advances. Involvement in endurance sports such as running and swimming should start with low intensity work-outs and gradually increase in intensity as the mother and fetus are able to tolerate.
It is important that the pregnant athlete carefully optimize their workout conditions. Pregnancy increases core body temperature. Maternal hyperthermia can have deleterious effects on the fetus. Exercise during the middle of a hot day should be avoided. Loose fitting clothes should be worn. The woman should be sure to stay adequately hydrated as well as carefully warm up and stretch before and after exercise. If at any time during exercise, the pregnant athlete becomes excessively tired or dizzy, nauseated, short of breath or overheated, they should immediately stop exercising.
What is exercise’s effect on the mother and baby?
Large studies of exercising women during pregnancy have demonstrated the safety of doing so in most cases. There is no increased risk of pre-term delivery or intrauterine growth restriction (stunted grow of the fetus). Women who exercise during their pregnancy gain less weight and deliver slightly earlier than those who do not. They also have less chance of a c-section and fewer complications during labor. It seems that women who had a moderate amount of exercise energy expenditure during their pregnancy experienced the best outcomes. No exercise at all and too extreme forms of exercise both had somewhat lesser outcomes.
How about exercise after giving birth?
As the physiologic changes from pregnancy resolve in the first 6 weeks postpartum, a female athlete’s exercise regimen may be increased in a controlled fashion. Moderate exercise does not effect lactation or neonatal weight gain in breast feeding mothers. Not surprisingly cardiovascular fitness will improve in postpartum mothers exercising regularly starting at 6 to 8 weeks after their delivery. It is important to monitor the mother’s caloric requirements during this period when their metabolism may increase at the same time as lactation further increases caloric requirements.
What are realistic goals of exercise during pregnancy?
The goal of exercise during pregnancy should be to improve overall fitness and to decrease associated disorders of pregnancy for both the mother and the fetus. Exercise can decrease the incidence of low back pain and leg swelling during pregnancy. Aerobic exercise defined as “repeated exercise that depletes cellular oxygen and places the body in a state of stress” is safe as long as the maternal heart rate is maintained within a safe range. A general formula for use is (220 – age) x 60 to 80% = target heart rate.
Furthermore maintaining a high level of fitness during pregnancy can allow for a rapid return to pre-pregnancy levels of fitness in female athletes. At the same time, pregnancy is not the appropriate time to reach peak physical fitness or train for athletic competitions. Short periods of submaximal exertion do not affect the fetus, but longer periods do. Transient fetal bradycardia (heart slowing) can occur as can placental steal syndrome. In this syndrome, blood preferentially goes to exercising muscles and shunts the placenta.
Elite pregnant female athletes who wish to train and compete should be closely monitored with regular obstetric follow-up. Care should be taken to monitor hydration, nutrition and body temperature.
Why is exercising in water most beneficial for pregnant athletes?
Water exercises have unique benefits during pregnancy. The hydrostatic pressure of water forces fluid from the extravascular spaces (fluid outside blood vessels) therefore decreasing edema, blood volume and uterine blood perfusion. The fetal response to exercise and uterine contractions may both be less with swimming compared with other dry land exercises. Furthermore, immersion in water is associated with a significant diuresis (urine production). Why this happens is not known, but it can be beneficial to controlling the normal swelling that occurs during pregnancy. Lastly, water assists with thermoregulation of maternal core body temperature.
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- Kalisiak B, Spitznagle T. What effect does an exercise program for healthy pregnant women have on the mother, fetus, and child? PM R. 2009 Mar;1(3):261-6.