There are many "rules" out there about what you can and cannot do when you're pregnant, and that is especially the case with exercise. The most common rules I heard was not increasing your heart rate above 140 BPM and to stop doing core work. Before I talk about any exercises I did while pregnant, I have to preface by saying, I am not a doctor or personal trainer. I was physically active before being pregnant and did consult with my midwife regularly about my exercise as my pregnancy progressed. I was also not a high-risk pregnancy, and do know there are many women out there that have to make modifications early on, or cease activity all together because of complications that come up.
10 Weeks Pregnant
Though my pregnancy as a whole was terrific, early in the first trimester I did have some complications that forced me to take a couple weeks off exercise. It wasn't bed rest, but I was encouraged to avoid all activity, including walking, as much as possible. Aside from this two week stint, I resumed my normal workouts. I continued with my normal core work, running, biking, lifting weights, doing HIIT and practicing yoga. I continued to do regular yoga, I hadn't switched over to prenatal yoga yet, as my belly hadn't grown at all, and it didn't feel awkward to be on my tummy, back, doing inversions, or twists. I didn't lift less weight when strength training, as is often recommended. Because your body starts producing the hormone relaxin, which causes your joints to become more loose, it is often recommended that you lift lighter. I did switch over to using more machines, rather than free weights, which reduce the risk of injury by offering a certain level of assistance, but continued to use the same weight. I didn't make any changes to my core work, running, biking or interval training at this point.
My HR was often above 190 BPM when exercising, but because this is normal and comfortable to me, my doctor and midwife didn't see any reason to be concerned. My doctor recommended using my perceived level of exertion as a means to measure if I was pushing too hard, rather than watching my heart rate monitor. He recommended that I not exceed a level of exertion that prevented me from talking while exercising.
Late in my pregnancy, when my HR monitor would pick up on my heart rate AND baby's HR.
While I understand not everyone will be able to maintain this kind of exercise regimen while pregnant, I think it's important to hear that there are women out there that can continue their normal workout routine after finding out they're pregnant. Of course, if anything feels uncomfortable, or not right, take that seriously and dial it back. Talk with your doctor or midwife about what they recommend, but understand that the recommendations you read on the Internet aren't going to be suitable for every women and every pregnancy. Use your intuition and do what feels best for your body and baby.
Two of my favorite blogs on pregnancy fitness are blondeponytail.com and fitnessista.com. I also subscribed to Fit Pregnancy and found it very useful throughout my pregnancy.