Should you continue to exercise if you’re a fitness enthusiast and pregnant? The conventional wisdom that resting during pregnancy is critical for the baby’s safety is not the case today. That is now an old wives’ tale.

There is no need to feel in a state of confinement during pregnancy nor worry about your fetus’ safety during exercise (at the appropriate level). 

Exercise plays a powerful role in the health of your pregnancy and long-term health of your baby. In fact, inactivity or sedentary behavior could be more detrimental on you and your child’s health. 

In this blog, we’ll talk about the irresistible health benefits that are in store for you and your baby. (Give away – it can be just 1 hour per week!)

Forget the Wives Tale That Pregnant Women Should Not Exercise

The American College of Obstetricians and Gynecologists (ACOG) recommends that pregnant women get at least 30 minutes of moderate intensity exercise on most (or all) days – as long as there are no medical or obstetric complications. Short duration strenuous exercise is suggested to not be of a concern to the baby, but it is unknown if long duration strenuous exercise will have consequences for the baby.

Unfortunately, a high percentage of pregnant women do not participate in any physical activity or exercise, which can increase their risk for obesity, gestational diabetes and other pregnancy-related conditions.  

Nonetheless, exercise may help with maternal weight gain, but there is no evidence that it can cause harm. It’s been reported that physical activity can have many benefits:

• Lower risk for gestational diabetes
• Better control of pregnancy weight gain
• Improve sleep, energy levels, mood and self-esteem
• Reduce and prevent lower back pain
• Prevent blood clots (i.e., thrombosis) and enlarged veins (i.e., varicose veins)
• Lower risk for depression after giving birth (possibly)

Deliver Your Baby at a Healthy Birth Weight 

The environment in your uterus can have a major influence on your child’s growth later on in life. Increased weight at birth is associated with obesity during childhood. Fortunately, exercising during pregnancy is a easy, smart strategy to lower your unborn child’s risk for childhood obesity.

Regular aerobic exercise, such as stationary cycling, can change the maternal environment that influences the nutrient status of fetal growth, which then lowers the baby’s birth weight. For example, a randomized trial assigned 84 mothers to either an exercise prescription, in which they completed stationary cycling for up to five, 40-minute sessions per week, or they were assigned to a control group. The exercise group had to follow their exercise program until at least 36 weeks of gestation. Even though the training had no effect on the maternal body weight or BMI near the end of pregnancy (compared to the control group), there were no issues regarding insulin resistance or other aspects of regulating blood sugar. 

So, exercise at the appropriate level does not put the pregnancy at risk and may have a long-term health benefit for your child. 

Boost Your Baby’s Brain

Add exercise during pregnancy and you could make your baby smarter. Measuring electrical brain activity is the best way to measure a newborn’s cognition. And that’s exactly what a study did to find that exercise during pregnancy enhances a newborn child’s brain development. The study had one group of women complete moderate-intensity cardiovascular exercise for at least 20 minutes three times per week during their second trimester. The other group of women were told not to exercise. Then the babies had their brain activity measured eight to twelve days after birth.

Newborns of mothers who exercised had 50% less electrical wave activity (meaning, the smaller waves use less energy to process information) compared to the newborns of mothers who did not exercise. Surprisingly, the women in the study barely completed an hour of exercise per week. 

Essentially, exercise during pregnancy can make a different in a child’s cognitive future. 

How To Tackle Exercise Challenges Near the End of Pregnancy

As you get closer to giving birth, it may take more energy to exercise. A study found that a woman’s Rating of Perceived Exertion (used to gauge the intensity of a workout) does not differ between moderate and vigorous intensity at any time point during pregnancy. But, in relation to how much energy was used, exercise was perceived to be the most challenging at 32 weeks. 

So consider changing the intensity of your exercise like decreasing the speed of a run. In fact, studies have shown that many recreational and competitive runners decrease their running intensity during the third trimester. Compete/train at a pace that allows you to breathe easily. But if you do not feel like you need to change your intensity, be mindful of any increased calorie needs.

And if you need lower intensity, strength conditioning exercise is an alternative. Light-to-moderate weight training using free weights or machines typically does not have any health consequences on pregnancy. Healthy women who completed strength training two times per week for 12 weeks experienced considerable strength gains. As for strenuous weight training (like a CrossFit class), there is no knowledge regarding the effects. It’s best to keep it light-to-moderate intensity. 

Practical Advice

Depending on what level of exercise you do, here is some guidance:

• Exercise Beginner or Recreational: if you currently exercise just recreationally or you want to start exercising, strive to complete around 150 minutes of moderate-intensity exercise (with a slight shortness of breath or about a six on an exertion scale from one to 10) per week. Examples of appropriate exercises include: walking, swimming and stationary cycling.
• Serious Exerciser: if you are currently someone who strenuously exercises (e.g., reaching ~70% of your maximum heart rate, “somewhat hard” or “hard” on a Rating of Perceived Exertion scale), discuss with your health care practitioner and trainer about your current exercise regimen. Closer supervision will be needed. For example, if you typically do CrossFit, Barry’s Bootcamp, HIIT classes and others that are similar, it’s important to tell the trainer about your pregnancy and ask how you could do the class at a lower intensity with modifications. (Remember: not enough maternal weight gain and poor fetal growth can result from too much exercise paired with not enough food intake.)
• Exerciser with a Personal Trainer: if you work with a personal trainer, be sure to tell them about your pregnancy so that they can make exercise modifications that will be safe for you. 

Ultimately, even light-to-moderate exercise is enough to have a positive impact on you and your baby. Simply discuss what exercises you can do with your health care practitioner and a certified fitness professional so that you exercise effectively and safely. 

Get active and get your blood flowing!