Back in the 19th century, pregnancy was considered a delicate condition that required confinement to the chaise longue in one's private sitting room. Today's wisdom is quite the opposite: Physical activity can do both you and your baby a world of good.
A woman who exercises is bound to weather the physical stresses and strain of pregnancy better. Moreover, working out helps you fight fatigue more effectively and motivates you to eat more nutritiously. The endorphins (feel-good chemicals produced by the pituitary gland) released during a fitness routine can give you a more chipper outlook even as your hormones take you on a roller coaster ride of mood changes. And by strengthening back and abdominal muscles, you can help ease back pain, a common complaint as ligaments stretch and your weight load increases.
Some ob-gyns have also found that expectant mothers who exercised regularly have an easier or shorter labor with fewer medical interventions. (Don't let the dream of a perfect delivery be your only motivation, however: The finding that prenatal exercise makes for better labor remains controversial, since many factors influence the length and course of labor.) Whatever the nature of your delivery turns out to be, it certainly stands to reason that mothers accustomed to physical exertion are better prepared for the rigors of childbirth.
One thing you shouldn't use an exercise program for right now, of course, is weight control. Losing weight by any means is not recommended during pregnancy.
Even if you're accustomed to regular exercise, don't expect to sweat in exactly the same way you did pre-baby. Your heart rate is higher now, for example, which means you won't have to work out as vigorously to get the same aerobic result. In fact, you'll want to take care not to overexert, since the pregnancy hormone hCG makes it much easier to get overheated now. Also, the strain on your respiratory system may make you feel winded. Another caveat: As the months go by and the hormone relaxin kicks in, your joints and ligaments soften, which may leave you more prone to falls, sprains, and other muscular injuries. All this on top of a swelling belly that throws off your center of gravity -- and your balance.
What do these changes mean for your current routine? It's hard to issue a one-workout-fits-all dictum for expectant women. Too much depends on your pre-pregnancy condition, the nature of your activities, and how your pregnancy proceeds in terms of complications or health risks. There are guidelines, however, that can help you begin an exercise program or modify the one you do now. Regardless of the workout you choose, one rule applies to all expectant moms: Always -- and that's with a capital A -- review your exercise plans with your doctor or caregiver.