Running 10k During Pregnancy: Safety & Considerations

Question
Good morning!

I really need some advice on this topic. My husband and I are trying to conceive and I have been racing 5k and 10k's every weekend (and have been for over a year). Do I need to go ahead and stop racing or can I wait until the pregnancy test confirms that I am actually pregnant? I have read everywhere that you need to cut back the anaerobic activity once pregnant and don't push yourself. However, is there any harm that can be done while racing, before you get the positive pregnancy test, since you are technically pregnant for 4 weeks by then? Can racing while you are 3-5 weeks pregnant harm the baby? I would greatly appreciate any help with this issue. I can't find any information about racing and the babys health for the first 4-5 weeks of pregnancy.

Thank you,

Answer
Generally, athletic women can continue to train at a high level until about the mid point of pregnancy, then slowly start to taper down the intensity of their training.

However, there has been one, (and to date only one) study done in Europe that shows a correlation between high volume/high impact/high intensity exercise and a slight rise in miscarriage in the first trimester. The reasons behind this result are still unclear. And no other studies have found this association. Athletically, a 5K is not that big of a run, 10K is is more taxing on the body. But neither are anywhere near a marathon or triathalon, or professional athletic training loads.

Aerobic exercise during pregnancy needs to be modified after 20 weeks, for that is when the placenta stops growing, and therefore its' ability to transport oxygen to the fetus is capped. I have read that some OBGYN's advise pregnant women to slow down during the first trimester, but other than the study that I've mentioned above, there does not seem to be a physiological advantage to slowing down.

In fact, I think that the opposite is true. Since aerobic exercise during pregnancy builds a larger placenta, and the first 13 weeks would cover 2/3 of this crucial first 20 weeks, it seems to me that to optimize maternal and fetal health, you'd want to stay as fit as possible while this window of growth is still open.

So this will come down to a judgment call on your part. If running a 5K would cause you an enormous amount of stress and anxiety, then don't. But if not running a 5K would be a major bummer, then maybe you should.

Certainly, you should be taking prenatal vitamins NOW. Adequate intake of folic acid, both before and during the first trimester, is very necessary for healthy fetal development.

For more information on aerobic exercise during pregnancy go to:
http://befitmom.com/aerobic_exercise.html