While it’s important to note that all the women in the study gave birth to healthy babies, the study sought to examine the formation of new blood vessels in the placenta. To do so, a sample of the placenta was collected for analysis within an hour of delivery. Though exercise is known to promote the formation of new blood vessels in order to deliver oxygen-rich blood to muscles more efficiently, whether it does so for the foetus was unclear.
Interestingly, the study found that there was a significant increase in levels of angiogenin, the key protein involved in stimulating blood vessel formation, in both exercise groups. There was little difference between those who did mild and moderate exercise, and no differences when it came to markers of low oxygen or other potential negative adaptations.
Basically, the study seems to support the evidence that already suggests exercise is greatly beneficial for pregnancy and women are encouraged to stick to the guidance of 150 minutes of exercise per week. As many have noted, keeping fit during pregnancy is essential, and for most what is hard is the disappointment of being unable to exercise. For some women, this is a result of problems like gestational diabetes or intrauterine growth restriction, conditions that exercise could actually prove helpful for.
Having said that, not all exercise is equal and the verdict is not out yet on just how hard pregnant women can train without seeing negative impacts. The rule of thumb has long stood with the suggestion that women should avoid getting their heart rate above 140 beats per minute, but many believe this to be outdated. Studies on Olympic athletes which saw them complete treadmill tests to exhaustion suggest that there is no evidence of lasting negative outcomes but still, researchers remain cautious when it comes to giving advice on exercising hard while pregnant. As many will be quick to tell you, the key thing is to seek medical advice, listen to your body, and ensure you stay hydrated and fed, and are alert to any discomfort.