Pregnancy and exercise

Abdominal Exercise


Below is the revised set of guidelines from the American College of Gynecologists as of 1994, from the ACSM's Guidelines for Exercise Testing and Prescription, 5th Edition (1995):

  1. During pregnancy, women can continue to exercise and derive health benefits even from mild to moderate exercise routines. Regular exercise (at least 3 times per week) is preferable to intermittent activity.

  2. Women should avoid exercise in the supine position after the first trimester. Such a position is associated with decreased cardiac output in most pregnant women. Because the remaining cardiac output will be preferentially distributed away from splanchic beds (including the uterus) during vigorous exercise, such regimes are best avoided during pregnancy. Prolonged periods of motionless standing should also be avoided.

  3. Women should be made aware of the decreased oxygen available for aerobic exercise during pregnancy. They should be encouraged to modify the intensity of their exercise according to maternal symptoms. Pregnant women should stop exercising when fatigued and not exercise to exhaustion. Weightbearing exercises may under some circumstances be continued at intensities similar to those prior to pregnancy throughout pregnancy. Non-weightbearing exercises, such as cycling or swimming, will minimize the risk of injury and facilitate the continuation of exercise during pregnancy.

  4. Morphologic changes in pregnancy should serve as a relative contraindication to types of exercise in which loss of balance could be detrimental to maternal or fetal well-being, especially in the third trimester. Further, any type of exercise involving the potential for even mild abdominal trauma should be avoided.

  5. Pregnancy requires an additional 300 kcal/day in order to maintain metabolic homeostasis. Thus, women who exercise during pregnancy should be particularly careful to ensure an adequate diet.

  6. Pregnant women who exercise in the first trimester should augment heat dissipation by ensuring adequate hydration, appropriate clothing, and optimal environmental surroundings during exercise.

  7. Many of the physiological and morphological changes of pregnancy persist four to six weeks postpartum. Thus, prepregnancy exercise routines should be resumed gradually based upon a woman's physical capability.

The changes in the 1994 guidelines largely are the removal of somewhat arbitrary restrictions on exercise session duration and maternal heart rate, as studies have demonstrated that earlier cautions were unwarranted, and that women tended to naturally adjust their exercise intensity with respect to the developing pregnancy.

The concerns about the 140 BPM maternal heart rate, exercise duration, and body core temperature were due to concerns that excessive maternal core temperature during exercise (especially in first-trimester women) might impair fetal development, as problems such as spinal bifida had been backtracked to excessive maternal core temperatures in some instances (such as when the mother was ill).

However, more recent research has demonstrated that women may exercise safely at higher intensities than previously thought, and that perceived exertion ("mild to moderate exercise") proves an effective safeguard when properly applied. Moreover, given the variation in ages of pregnant women, plus the wide variation of maximum heart rate in the general population, an arbitrary maximum heart rate specified by a single number was virtually meaningless.

More on elevated core body temperature during pregnancy

ACSM also lists several reasons to discontinue exercise and seek medical advice during pregnancy:

  1. Any signs of bloody discharge from the vagina.
  2. Any "gush" of fluid from the vagina (premature rupture of membranes).
  3. Sudden swelling of the ankles, face, or hands.
  4. Persistent, severe headaches and/or visual disturbance; unexplained spell of faintness or dizziness.
  5. Swelling, pain, and redness in the calf of one leg (phlebitis).
  6. Elevation of pulse rate or blood pressure that persists after exercise.
  7. Excessive fatigue, palpitations, chest pain
  8. Persistent contractions (>6 to 8/hour) that may suggest onset of premature labor.
  9. Unexplained abdominal pain.
  10. Insufficient weight gain (<1.0 kg/month) during the last two trimesters.

ACOG also lists several contraindications for exercising during pregnancy:

  1. Pregnancy induced hypertension.
  2. Pre-term rupture of membrane
  3. Pre-term labor during the prior or current pregnancy
  4. Incompetent cervix
  5. Persistent second to third trimester bleeding
  6. Intrauterine growth retardation

ACOG also differentiates between women who are established exercisers before pregnancy vs. new exercisers. Women who exercised regularly before pregnancy can continue their exercise programs (making appropriate adjustments) during pregnancy. New exercisers are encouraged to seek physician approval, and to participate in low-impact activities, like swimming or cycling.

Abdominal Exercise

Working your abs during pregnancy is safe as long as your rectus abdominus does not separate. You can check this by doing a sit-up half-way up and trying to stick your finger in the middle of your abs an inch or two below your belly button (this is hard to explain, but easy to do). If you can two fingers in, it's time to discontinue ab work - or at least use your hands to support the sides of your belly - check with your doctor, of course.

Given that, after your 4th month you shouldn't do any exercise in the supine position ( the extra weight could block the blood flow to the fetus). So to get around that, do your sit ups in a decline position. Using a bench with 2-3 blocks on one end and none on the other end then laying on it with your head at the high end accomplishes this very easily.

This worked very well for me, I used a decline bench to do my sit ups up until the day before I went to the hospital to have my daughter. I really believe that it made getting back in shape a lot easier afterwards.

From: (Martha Dumler)

Posted to Stefan McDonald wrote:

I've heard that pregnant women should not sit in hot baths or saunas because the heat that builds up in the body can harm the unborn baby. How does this figure with aerobics? When I do my aerobic routine I get very overheated.Is it bad for a pregnant woman to do a vigorous aerobic routine?

Larry Deluca responded

There has been a lot of controversy surrounding this topic. Up until 1994 the American College of Obstetricians and Gynecologists recommended keeping the maternal exercise heart rate at 140 BPM or below during pregnancy in an effort to (indirectly) prevent maternal core temperature from exceeding 38C.

However, the large number of women who have trained at higher intensities during pregnancy with no adverse effects coupled with the fact that there is no research to support any sort of correlation between exercise heart rate and increased birth defects or pregnancy complications has caused ACOG to revise their guidelines, and suggest that pregnant women exercise at a "mild to moderate" intensity, acknowledging that most women will tend to adjust their exercise intensity automatically as their pregnancy progresses.

Pregnant women are advised to ensure adequate means of heat dissipation, including comfortable, loose-fitting clothing that will allow sweat to evaporate, and to be aware of an optimal exercise environment, especially during the first trimester.

Some organizations recommend the avoidance of saunas, hot tubs, etc., but ACSM/ACOG make no specific recommendations in this regard (at least not according to GETP, 5th Ed.). However, given the other warnings I would advise pregnant clients to consult their obstetricians for further guidance.



The information is not a substitute for medical advice. You are responsible for protecting yourself from injury to yourself and your baby. We strongly recommend that you discuss this with your doctor before implementing it as part of your exercise routine.
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