Congratulations! I'm 27 weeks (6 months) along. My worst balance issues were around 6 - 9 weeks, I think stayed off the bike for 2 weeks then, but then my balance came back. I cut back on the intensity a bit, no all out efforts. I had morning sickness and nausea all day from weeks 7 - 13, so I didn't really feel like pushing it anyway. I did my first sprint tri at 11 weeks, but took it really easy. Then around 17 weeks my knee started hurting on my morning commute (20 miles). After talking to some people, I'm pretty sure this was due to my loosening hip joints which were in turn affecting my knee. I made some saddle and cleat adjustments and was able to do a few more short (10 -15 mile) rides. Now due to lack of day light, a rapidly expanding belly, bad weather, and other life chaos, I haven't ridden since mid September, around 19 weeks. I did go to a spinning class which was ok, except for standing, couldn't do that or I'd get the same knee pain. I really don't think I could even fit on my bike now with the belly, perhaps the mtb.

I have kept up running, step aerobics, walking, and weight training though. I'm determined to keep exercising as long as I can. I just ran a 5 k last Saturday at a very slow pace, but I did run the whole thing.

With all of the physical changes of pregnancy, it's common for female athletes to be frustrated by their apparent decrease in fitness. I started getting really pissy when I'd get out of breath climbing a flight of stairs. I had to have it explained to me that it doesn't mean I'm out of shape, just pregnant. I started noticing it around 15 - 16 weeks, it just got harder to do everything all of a sudden. Then when the baby is big enough that s/he is pushing on your lungs, oh the joy.

If you haven't already, I'd recommend reading "Exercising through your pregnancy" by Dr. James Clapp. His group has done a lot of research on pregnant female athletes (both serious and recreational). I found it very helpful, it was recommended by Lenusik here on TE (is she still here?). I will say that even though I'm still exercising, I'm looking forward to some tough workouts after the baby is born. I just don't feel comfortable going all out while pregnant, and I miss it. Good luck!