But low-impact exercise offsets hormonal changes that weaken the joints. "During pregnancy, the body secretes relaxin to widen the birth canal, but it loosens up all the other joints too," says Lisa Stone, deputy director of the Georgia Commission on Physical Fitness and Sports and founder of "Fit for 2," an exercise program designed for expectant mothers.
Stone, who is certified as a pre- and postnatal fitness instructor by the American Council on Exercise, tells WebMD that strengthening exercise stabilizes the joints and stretching exercise prevents muscle strains. Aerobic exercise, a third Fit for 2 component, burns fat and holds weight gain to a healthy maximum of 25-35 pounds.
Pregnant women should also drink plenty of water before, during, and after exercise. "Unlike you, your baby can't sweat to prevent overheating," says Stone. "So it's a good idea to take a swig of water every 10-15 minutes. Another rule of thumb is to stop exercise well before the point of exhaustion."
"I was running five miles a day until I became pregnant, but I had to stop because it was too uncomfortable," says first-time mother Shannon Powers-Jones, a freelance writer in Atlanta, who adds that exercise helped improve her psychological health.
- Low back, hip, and calf pain often experienced during pregnancy can be prevented with stretching, strengthening, and aerobic exercise.
- In compensating for changes in body weight and distribution, regular exercise helps prevent overuse injuries, particularly in the pelvis, hips, and ankles.
- Exercise offsets hormonal changes that weaken the joints, but sit-ups and weight training should be avoided after the first trimester, particularly in women at risk for preterm labor.