When you're exercising for two

THERE ARE moments in our lives that we remember forever. We remember our first kiss, our prom and the breathtaking moment when the home pregnancy test has confirmed it - yes, you are pregnant!

For expectant mothers who exercise, one question quickly arises: Should I keep this up?

With some important exceptions that you'll want to ask your doctor about, the American College of Obstetrics and Gynecology (ACOG) says that pregnant women "should be encouraged to engage in regular, moderate-intensity physical activity" to keep enjoying the same health benefits during their pregnancies as they did before that life-changing test came back positive.

Research also indicates that exercise during pregnancy can improve a mother-to-be's sense of well-being, increase her energy and help her to sleep better.

Naturally, there are limits. Pregnancy is definitely not the time to take up contact sports like basketball, nor is it the time to train for your first marathon. (It's also not the time to curl up in bed for nine months with your favorite flavor of Ben & Jerry's. A friend of mine made that mistake and ended up gaining an extra 90 pounds during her pregnancy.)

But if you use common sense, you can probably continue your favorite workout, with some adjustments. Check with your doctor to make sure that the yoga classes and aerobic workouts that you enjoy - and the weight-training routine that you follow - are still OK, given the particulars of your pregnancy.

Some general guidelines:

* After the first trimester, avoid doing any exercises that call for you to lie on your back.

* If you are new to exercise, take it easy. Low-impact cardiovascular exercises like walking and swimming are good choices.

* Avoid brisk exercise when it's hot and humid, and drink lots of water to stay hydrated at all times.

* If you've been training with weights, you may need to modify the frequency, duration or intensity of your workout. Concentrate on maintaining good muscle tone. This is not the time to begin your power-lifting career.

* Based on some preliminary studies, yoga seems to improve expectant moms' well-being and even help with labor. You may want to look into classes specifically designed for pregnant women.

* While you should expect to gain weight during your pregnancy, there is no need to go overboard indulging in treats. According to ACOG, underweight women should gain 28-40 pounds, normal-weight women 25-35 pounds, overweight women 15-25 pounds and obese women 11-20 pounds.

* Kegels are your friend. Don't forget to add pelvic-floor exercises to your routine.