TUESDAY, March 15, 2005 (HealthDay News) -- It wasn't all that long ago that the moment a woman learned she was pregnant, exercise was out and pampering and rest were in.
It was imperative, the thinking went, that the mom-to-be do nothing to risk her baby's development.
Today, doctors say not only is it OK to exercise, but women should stay active as a way to ensure a smoother, healthier pregnancy and delivery, while possibly reducing the risk of gestational diabetes.
Dr. Mary Jo O'Sullivan, a gynecologist and professor emeritus at the University of Miami in Florida, said that in the past, "women were catered to when they became pregnant," because it was assumed physical activity would harm the fetus.
But recent research has found that fetal heart rate and birth weight don't suffer when a healthy woman exercises moderately. Nor does exercise harm the placenta, the organ that grows on the wall of the uterus and supplies blood and nutrients to the baby, O'Sullivan said.
"In a basically healthy woman, a moderate exercise program does not seem to have a significant impact on the pregnancy as far as the fetus is concerned," she said.
Karen Fehr, division chairwoman of health and exercise science at Paradise Valley Community College in Phoenix, added, "Exercising helps women to have the energy levels and endurance to maintain strength during the changes in the body due to pregnancy."
What's more, exercise can help reduce some of the typical pregnancy discomforts, such as backache, constipation, fatigue, bloating and swelling. And it boosts a woman's mood, energy level and self-image, while improving her posture and sleep, according to the American College of Obstetrics and Gynecology.
Fehr added, however, that exercise has to be tailored to a pregnant woman. For instance, pregnant women shouldn't exercise on their backs because the baby's weight can press too much on the lungs and arteries. Also, exercises have to account for changes in balance and body mechanics because of the extra weight of the stomach and lower center of gravity. Also important is proper exercise technique, she added.
During pregnancy, a hormone called relaxin is released into the body to relax the uterus to make room for the growing fetus. But this hormone also relaxes all the other connective tissue in the body, like the ligaments and tendons that surround the joints.
"These hormones can cause joint laxity," Fehr said, so women need to be careful when putting stress on their joints.
Three years ago, in response to questions about exercise during pregnancy, the American College of Obstetrics and Gynecology issued a set of guidelines to help women and doctors.
In general, said O'Sullivan, who helped prepare the guidelines, swimming and walking are recommended, as well as aerobic activity at half the level of pre-pregnancy.
Not recommended, according to the guidelines, are contact sports or activities that carry a risk of falling, both of which could cause harm to a fetus. These include sports such as soccer and basketball, rigorous racket sports, and activities such as downhill skiing or horseback riding, she said.
The guidelines also list physical conditions that preclude any exercise, like high-risk pregnancies, second or third trimester bleeding and heart disease, and conditions that call for caution in exercising, like severe anemia, poorly controlled high blood pressure or type 1 diabetes, obesity, or a previously sedentary lifestyle.
O'Sullivan said that, despite the booming interest in exercise among women, very few actually exercise during pregnancy.
"This is a very rough estimate, but no more than 15 percent of pregnant women are exercising," she said, "and those who do are in a higher socioeconomic group, who are generally thin, and who are exercising pre-pregnancy."
Besides the heart, there are three muscle groups women should focus on during pregnancy -- the muscles of the back, the pelvis and the abdomen, according to the University of Michigan Health System:
- Strengthening abdominal muscles makes it easier to support the growing weight of a baby. And you'll be better equipped to push with more strength and effectiveness during labor.
- Building up pelvic muscles will allow the vagina to widen more easily during delivery. It may also help prevent urinary problems after delivery.
- Working on back muscles will make them stronger, improve posture, and lessen the strain of pregnancy on your lower back.
Fehr, who first designed an exercise class for pregnant women about 15 years ago, said a big trend in pregnancy exercise today is yoga classes.
"Yoga has become so popular that we offer it instead of regular fitness classes. Yoga offers stress reduction and encourages mental well-being, but you do have to supplement it with cardiovascular exercise," she said.
For more on exercise during pregnancy, visit the University of Michigan Health System.