Are Exercise and Athletic Training Safe During Pregnancy?

By Rachel Kramer, MD, OB/GYN—Virtua Obstetrics & Gynecology

Being active during pregnancy is one of the healthiest things you can do for yourself and your baby. If you’ve never exercised before, or have been an athlete your entire life, it’s possible (and recommended) for you to develop and/or maintain a safe and consistent workout routine while pregnant.

Guidelines for exercising during pregnancy

The benefits of exercise during pregnancy are numerous. In addition to preventing excessive weight gain, helping to control gestational diabetes and reducing nausea and vomiting, exercise also boosts energy levels, reduces stress and improves your overall mood. However, it’s important to discuss your fitness routine with your obstetrician regardless of your pre-pregnancy activity level.

If you experience or are at risk for conditions such as bleeding, preterm labor, pre-eclampsia or problems with your placenta or cervix, your doctor may advise you to avoid exercise.

In the past, pregnant women were advised to keep their heart rate under 140 beats per minute while exercising. But, there’s no medical evidence that shows a higher heart rate is harmful. As long as nothing is hurting, you’re not breathless and unable to get out a sentence, and you’re drinking plenty of water, there’s no reason to be concerned about your heart rate—even during a vigorous workout.

Regardless of how far along you are in your pregnancy, pay close attention to how you’re feeling during and after exercise. As your pregnancy progresses, you may notice a decline in your athletic performance. You also may need to modify your workout to accommodate your growing belly and other physical changes. Here’s a rundown of expectations during each trimester.

First trimester

During your first trimester, you may struggle with nausea, vomiting and fatigue. Despite these challenges, it’s generally safe to stick to your pre-pregnancy workout routine. If you’ve never exercised before, the first trimester is a great time to begin walking, swimming or indoor cycling.

Many women discover exercise helps relieve vomiting and nausea while providing a much-needed energy boost. Also, try to eat a variety of healthy foods, but don’t worry if you aren’t feeling up to it. Even if you’re exercising, the body doesn’t require additional calories during your first trimester. Unless you’re training at the level of an Olympic athlete, aim for about 1,500 to 1,700 calories per day.

Second trimester

During the second trimester, your growing belly may render you a bit off balance. It’s important to avoid any activity with a risk for falling, such as outdoor cycling (indoor cycling or spinning is fine) or running on uneven surfaces. Many women also enjoy exercising at the gym during the second trimester thanks to amenities such as climate control and nearby bathrooms.

Because your blood vessels begin to dilate around 16 weeks, you may feel faint when you exercise. If this occurs, slow down or stop exercising until the feeling subsides. Before and during exercise, drink a sugar-free sports drink with electrolytes to prevent lightheadedness. Or, before exercise, have a snack that combines protein with carbohydrates, such as half a banana with a tablespoon of peanut butter.

As your nausea and vomiting subsides, try to eat healthy foods such as leafy greens, salmon, olive oil, nuts and nut butters. Aim to consume about 300 extra calories per day for a total of 1,800 to 2,000 calories. Although taking a prenatal vitamin is important, studies show that pills are less effective than a healthy diet when it comes to providing the nutrients you and your baby need. 

Third trimester

It’s quite common to have problems with balance, joint pain or swollen legs and feet during your third trimester, which makes swimming a great fitness option. Lap swimming, water aerobics and water running will tone your core, increase your heart rate and take pressure off your legs and joints. Yoga and stretching also can help keep you toned.

Even if you’re feeling great in your third trimester, hold off on competitive fitness activities such as marathons after 36 weeks. Although running a marathon in your third trimester wouldn’t necessarily cause you to go into labor, the crowds and closed streets common during this type of event can be a bad combination if you sustain an injury or go into labor naturally and need to get to a hospital.

Just as you did in your second trimester, continue eating a balanced, nutrient-rich diet that's about 1,800 to 2,000 calories per day.

Postpartum

You should wait until at least 6 weeks after giving birth to resume vigorous exercise. However, you can begin light exercise such as walking or stretching as soon as you feel up to it. After your doctor gives you the green light to resume your exercise regimen, start slowly and gradually increase the intensity as you become stronger. 

You can breastfeed even if you’re exercising or training—just make sure you’re drinking plenty of fluids. It’s also a good idea to breastfeed or pump prior to exercise to avoid engorged, painful breasts. 

Virtua offers a variety of pre- and post-natal fitness classes, as well as baby and me classes. To register or for more information, call 1-888-VIRTUA-3. 

Updated April 23, 2018