Get Moving

(Here are some other good ideas for working out during your pregnancy and staying fit.)

Women who don't lose their baby weight after six months are more likely to be overweight a full decade later.

Use these nine months to find an activity you enjoy that won't be too tough to continue after your tot makes his entrance. Aim to exercise at least 30 minutes a day, most days of the week, but watch the intensity: If you can't talk without gasping, you're working too hard.

5 great activities to try

Walking
Why it's wonderful now It's easy, effective and can be done in 10-minute sessions if you get winded easily. Walking is also low-impact, which keeps stress off your joints so there's less chance of injury.
Keep in mind Avoid uneven or slippery surfaces--you're more prone to fall as your belly grows and your center of gravity shifts. Plus, your body is producing more relaxin, a hormone that causes the ligaments in your pelvis to soften. "Although this is helpful for delivery, it also means that all your joint ligaments become more lax, making you more likely to twist or sprain your wrists, ankles and knees," says Anita Sadaty, M.D., attending physician in obstetrics and gynecology at North Shore University Hospital in Manhasset, N.Y. Cross trainers provide more lateral support than running shoes; you may need to go up a half size by your third trimester.
How to adapt it later Put your baby in a front carrier (later, a baby backpack), and pick up the pace by bending your arms and driving them back as fast as you can. Seek out hilly neighborhoods or scenic hiking paths you may have avoided for safety during your pregnancy.

Swimming
Why it's wonderful now Water provides resistance with a low risk of injury, allowing you to work harder without overheating, whether you're treading it or swimming, walking or even dancing in it. And even in your ninth month, you can still look and feel graceful in the pool. (We promise!)
Keep in mind Swimming with poor technique could make neck, shoulder or back pain worse. Stop if you're hurting.
How to adapt it later Raise a water baby! Check into mommy-and-infant water programs at the YMCA, your local gym or a swim center.

Pilates
Why it's wonderful now Pilates strengthens all your core muscles, helping to lessen lower-back pain.
Keep in mind Avoid lying flat on your back during the second and third trimesters; speak to your instructor about using a wedge, pillow or bolster to keep your head higher than your belly while performing exercises.
How to adapt it later Pop in a Pilates DVD while your baby is napping, or ask the instructor at your local gym if it's OK to let your child watch in a carrier from the sidelines (free entertainment for your baby!).

Yoga
Why it's wonderful now Yoga improves balance, which is affected by pregnancy body-weight shifts; relieves stress with breathing and meditation techniques; and helps soothe the aches and pains of pregnancy. Yoga postures can also open hip joints, which could benefit you during delivery, says Chicago certified personal trainer Michael Sena, author of Lean Mom, Fit Family (Rodale, 2005).
Keep in mind Avoid inverted and extreme positions, especially those in which your legs are far apart (like Pigeon or Tailor pose). Although relaxin will allow you to stretch farther than usual, this can lead to muscle tears, so take it easy. Also, avoid lying on your back after the first trimester. Prenatal yoga is safe for all trimesters, and (bonus!) you may meet some new friends.
How to adapt it later Try power yoga to work up a sweat and build muscle endurance. Put your baby in a bouncy seat next to your sticky mat (or give your baby his own). Some studios also offer mommy-and-me yoga classes.

Strength training
Why it's wonderful now Lifting weights helps counteract the higher risk for injury during pregnancy by strengthening muscles surrounding the joints, Sena says. It'll also help prepare you for the heavy lifting of motherhood.
Keep in mind Make sure to breathe in and out evenly, rather than tax your pelvic area by exhaling too forcefully. You'll avoid overloading your loosening joints by working to fatigue (doing a lot of reps) using lighter (3- or 5-pound) weights rather than 10-pounders.
How to adapt it later Shoot for heavier weights that you can lift for only about 8 to 12 reps. If you're joining a gym, make sure it offers day care--many do--at hours that fit your schedule. And find a good postnatal DVD.