The safety of moderate intensity exercise during pregnancy has been well established. Walking, swimming and using an exercise bike are all activities that could be considered moderate intensity.
Expectant mothers who do at least 150 minutes of moderate intensity physical activity per week, are healthier, happier, stronger, and develop fewer complications like gestational diabetes and pre-eclampsia.
Expectant mothers receive an avalanche of information about potential risks to their baby. There’s a growing list of foods, toxins and environmental threats to avoid. It’s normal for this to lead to an increased level of anxiety.
As a result, some women believe it’s safer to avoid any risks in pregnancy, no matter how small. Vigorous exercise may be considered one of these risks.
What we found should be reassuring for active women with healthy pregnancies: vigorous exercise appears to be safe for both mum and baby, even when continued into the third trimester.
The studies looked at a range of outcomes for both mum and baby, and none showed any meaningful increase in risk. There was no difference in birth weight of babies when their mums did vigorous exercise; and in particular no difference in the number of babies born small for gestational age.
For women in the healthy weight range, vigorous exercise didn’t affect the amount of weight they gained during pregnancy. That is, they followed the expected trajectory of weight gain as their pregnancy progressed.
But, in overweight and obese women, for whom it can be more difficult to adhere to the recommended weight gain during pregnancy, vigorous exercise did appear to reduce maternal weight gain.
High-intensity and high-impact exercise in Pregnancy
Exercise at greater than 90% of maximum heart rate is considered “high-intensity ”. This is where you can’t even string a sentence together.
We don’t yet know if high-intensity training carries any risks, so there’s still a limit to what mums might want to do later in a pregnancy. We’d recommended mums do the “talk test” to make sure they can still speak while exercising.