From the moment you find out you’re pregnant until the birth of your baby, exciting and overwhelming changes characterize your life and body. Many women worry about their ability to maintain an active lifestyle during pregnancy or hope to prevent excessive weight gain. Other women consider beginning an exercise program as part of an effort to make better lifestyle choices and deliver a healthy baby.
What do we know about the safety of exercise during pregnancy?
Every woman and every pregnancy is completely different. That’s why it’s critical to work with your obstetrician to decide on your activity plan. Certain medical conditions put you at risk for injuring either yourself or your baby. Listen to your doctor. Pregnancy is NOT the time to charge into a vigorous regimen of exercise, especially if you’ve been a couch potato! However, there is good evidence to suggest that a healthy woman can begin or maintain a program of regular moderate exercise during her pregnancy. If you’re an athlete, athletic performance doesn’t seem to be affected during the first 2-3 months of pregnancy. You may be able to continue training well into your pregnancy (depending on your sport). Work with your doctor to modify your exercise intensity and training schedule.
There are several studies which show that fit and active women can exercise vigorously during pregnancy and deliver healthy babies. Women who exercise regularly report feeling better during their pregnancy than sedentary women and may gain less fat weight.
Guidelines for Exercise
Cardiovascular activities that are low-impact or non-weight bearing (swimming, walking, cycling) have the best potential to be carried on throughout your entire pregnancy. Water aerobics or swimming not only minimize joint stress but can reduce fluid retention. Other forms of regular aerobic exercise might include aerobics classes (particularly low impact), stairstepping, jogging, hiking, elliptical trainers and cross-country skiing.
How hard? Standard target heart rate formulae are probably somewhat flawed due to cardiovascular and blood flow changes during pregnancy. There is some evidence that vigorous intensity exercise (above 150 bpm) causes bursts of rapid heart beats in the fetus which may be an indicator of stress. It’s probably best to exercise at a moderate level based on your own feelings of exertion. However human studies have not shown bad effects on mother or baby when exercising at vigorous intensities or using traditional heart rate ranges. Standard recommended intensities are 60-75% maximum heart rate for the unfit woman and 70-85% for the regularly exercising woman. Subjective feelings of exertion have been shown to be a more reliable indicator of work intensity during pregnancy than heart rate. Listen to your body! Pregnant women often naturally lower exercise intensity during late pregnancy. Smart move, ladies!
How often? Avoid the "weekend warrior" syndrome. Ideally, a pregnant woman should perform cardiovascular exercise at least 3-4 days per week. If you exercise more frequently, consider a variety of activities (to reduce overuse injuries) and drink plenty of fluids.
How long? Short aerobic exercise intervals (15-20 minutes) may help prevent heat stress to you or your baby. However there is no evidence to suggest that a more typical 30-60 minute workout is harmful.
Strength Training: Strong muscles will prepare you for the lifting required when your new baby arrives, along with the associated paraphernalia you’ll be lugging around (car seat, stroller, diaper bag). Depending upon your intended delivery position you’ll need good strength in your "squatting" muscles. Low back pain, a common complaint of pregnant women, can be helped by specific strengthening and flexibility exercises. A physical therapist who understands your body’s changes during pregnancy is in the best position to suggest specific exercises.
Correct posture, breathing and lifting technique are very important. Avoid straining or holding your breath during challenging lifts. The use of exercise machines rather than free weights is probably smarter in latter pregnancy when normal balance is disrupted. Since not much information is available about heavy lifting during pregnancy, it’s best to avoid heavy loads and use a standard conditioning approach: 8-12 reps, 1-3 sets, to momentary muscular fatigue, 2-3 times/week.
The American College of Obstetrics and Gynecology recommends that women avoid exercise while lying on their backs after the first trimester because this position can decrease blood flow to the baby. For example, pelvic tilt exercises can be performed in the side-lying, sitting, standing or "all fours" positions. Prolonged, motionless standing should also avoided.
Do you lose urine when sneezing, laughing, coughing, jumping or exercising? Pelvic floor exercises are critical to prevent stress incontinence (involuntary loss of urine) during pregnancy and in preparation for postpartum recovery. A physical therapist or childbirth educator can provide expert instruction.
Balance/Coordination: If you play tennis, squash, ski, dance or participate in other activities requiring agility or balance, remember that hormone changes after 28-30 weeks will loosen your joints and make you more susceptible to injury. Increased body size, altered center of gravity and changing posture will also begin to slow your movements, affect your balance, change your body mechanics and make you work harder. Use common sense! Consider cross-training or adopt some alternative, safer exercise activities during the latter stages of your pregnancy.
Sports activities that challenge your ability to get oxygen such as mountain climbing or scuba diving should be avoided. Snorkeling is fine during pregnancy, but deep sea diving may cause decompression problems in the fetus and should not be done. A healthy, non-acclimatized pregnant woman should not exceed an altitude of 8,000 ft during the first 4-5 days of short-term altitude exposure. Exercise activities such as climbing or cross-country skiing should be done at even lower altitudes.
After 20 weeks, sports that carry the risk of falls or abdominal trauma may also be a problem. For example, contact sports like soccer and basketball, gymnastics, skiing, hang gliding, horseback riding and vigorous racquet sports may cause premature labor or injuries. This is the time to rely on other forms of exercise.