Running sneakers and baby bumps

running while pregnant in third trimester

Confession: I hate running.

But I like to stay in shape and running is the most convenient form of exercise for me so I lace up and run.

When I got pregnant with my first, I thought:  “Sweet, now I have an excuse to stop running!”.  But, alas, the inner athlete in me refused to die with my expanding belly.

Running falls into the same trap as most pregnancy “advice” (both solicited and unsolicited) – one person will say “you need to slow down!” and the next will say “didn’t so-and-so run a marathon when she was 8 months pregnant?” (Yes, she did)

The wide world of internet advice seems to stay a bit vague on this issue.  More than once, I have seen or overheard the magic number of “140” (mom’s heart rate in beats/minute) floating around despite the fact that a little bit of investigation suggests that this recommendation was nixed in 1994 by the American College of Obstetricians and Gynecologists. But mostly, the advice is simple:  if you are overheating, if you are throwing up, if you are bleeding or passing out, stop your workout. Seems a bit obvious to me.


Ok, on to the science of running and pregnancy

A lengthy 2003 review in The British Journal of Sports Medicine scanned the data available throughout the scientific literature and found evidence (and lack of evidence) for the pregnant exercise dilemma.  The authors conclusion:  “exercise has minimal risk and confirmed benefits for most women.”

Did I fall into the category of “most women”?  Not going to flatter myself, I probably did, but just in case, I dug further…

A 2012 study in the American Journal of Obstetrics and Gynecology categorized women into their exercise regiments and measured parameters of both mama and womb baby.  Pregnant ladies ranging from 28-32 weeks were split into three groups: inactive, moderately active, and highly active.  They were then tested before and after moderate and vigorous exercise (luckily for inactive group, they weren’t pushed to the vigorous stage so this category only contains those who exercised a bit before the test).  Measuring maternal heart rate (MHR), fetal heart rate (FHR), and indices of circulation making it between the two (via measurements from fancy Doppler sonography), the authors reached the conclusion that moderate exercise, even for the previously inactive pregnant ladies, does not change a single thing for the baby’s measurements.  Only vigorous exercise caused changes – slight increase in FHR but a decrease in Doppler indices. Interestingly, this decrease actually indicates improved circulation to the baby, making this change “not clinically significant”.


What about pregnant elite athletes?

There’s a category that I definitely do not fit into:  elite athlete.  But just in case, I checked out an article entitled “Fetal Wellbeing May be Compromised During Strenuous Exercise Among Pregnant Elite Athletes”, a 2012 study The British Journal of Sports Medicine. However, I quickly lost attention when I realized that this study was conducted on SIX women and the only result they found (increased FHR) occurred when these Olympians, training for endurance events, were pushed to >90% of their maximal heart rate.

Basically, if you are training to run a marathon in 2 1/2 hours, you might want to shoot for a 3 hr pace instead when you are running for two.

I guess I don’t have to worry about that one.

In the end, I ran out of excuses so I laced up and headed out for the door. Bump and all.

(Epilogue: I stopped running around 28 weeks with baby #1 and 18 weeks with baby number two – turns out there are comfort reasons to stop running while pregnant!)


For more information about the benefits of exercise during pregnancy and which activities to explore or avoid (looking at you pregnant SCUBA aficionado) – head over to ACOG’s page on the subject.

 

This post was adapted from it original piece on thepregnantscientist.com

Photo credit: San Diego Shooter via Visualhunt.com / CC BY-NC-ND

About the Author

Molly leads Content and Community at Bloomlife and edits the Bloomlife newsletter. She likes to puts her PhD in Physiology to good use by digging into the scientific literature to share fun facts about pregnancy and parenting along with a few busted myths backed by solid research studies. Yay science!

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