I wrote this post - Bump on Board: Running in Pregnancy - on my blog some time ago but would be interested to hear the comments/thoughts of other avid running moms about running in pregnant. Check it out and let me know what advice you were given on running while pregnant.
Thanks for the comment and good luck with all your running adventures....I see from your blog that you are aspiring towards the 50+ marathon club - that's amazing and definite commitment! I love my running and I did the London marathon in 2008 but I'm not sure I could hack that distance with regularity but I would like to do the NY marathon one day since that's where I'm originally from. Here's to keeping the pace in 2010~
I've been running for the last 4 years, but stopped for about 6 months and then found out I was pregnant. My doctor (thinking I was still running twice a week) told me to go ahead and keep running. If I was still running regularly at that time, I definitely would have kept it up throughout my pregnancy. I was so disappointed that I entered my pregnancy during a fitness lull. I joined a gym instead and worked out 2-3 times a week (low impact), building my endurance and core strength back up. I also rode my bike right into my 3rd trimester which got the same reaction you describe in your article. I rode an old retro style ladie's bike with a big comfy seat (with springs and everything) and I stayed on bike paths. I've been riding my whole life so I felt very safe. I also felt free and weightless which was wonderful during the really hot months. Cycling hadn't occurred to me during my first pregnancy but I was inspired by an article in Fit Pregnancy magazine that featured women who ran and biked right up to their due date.
Generally it is plenty safe to exercise at the duration and frequency of what you're used to doing prior to getting pregnant. There are just a few certain exercises and activities to avoid for safety reasons. I would definitely communicate with your doctor, however, and get and 'ok" prior to doing anything. Better safe than sorry!
I'm a pre/postnatal exercise specialist and personal trainer. If you guys ever have any questions, feel free to ask :)