DH and I decided around the time our son was 11 months old that we wanted to start trying for our second. So I stopped breastfeeding and a week later got my period. As soon as we had made the decision, I started to train HARD; I knew full well that I wouldn't be able to train at that intensity once I got pregnant, so I trained to my fullest capacity while I could.
Lifting heavy - Due partially to lowered strength, partially to a restricted range of motion, and partially to a concern for safety, it becomes more difficult for me to lift super heavy when pregnant; I took full advantage of my strength while I could.
Plyometrics - As my belly gets bigger, it becomes uncomfortable to be jumping around. It's also a safety concern to be box jumping really high boxes (even on a good day, I tend to bail at least once :P). After I had finished a heavy lifting phase, I did a few weeks of really challenging plyometrics.
Inversions - Ok, there was really just one inversion. I incorporated some handstand practice into my cool-down routine as I don't really like the idea of being up-side down as I become more pregnant. Here's an article I found about the safety of inversions during pregnancy: http://www.90monkeys.com/2013/09/downward-facing-yoga-mama-inversion-issues-during-pregnancy/
Sprints - I'm not much of a runner, but when I do I like to SPRINT! Only thing is, that's a lot of bouncing around when you've got a big belly. It's also very very intense. So I did lots of post-workout sprint work on the treadmill and outside.
Stretching and Relaxing - My chiropractor had told me that my adrenal glands were way too active, and that I would have a hard time conceiving until I calmed myself down a bit. So I made an effort to get more sleep, I practiced positive thinking in stressful situations (a one-year old throwing a fit at the grocery store can be pretty dang stressful!), I took deep breaths whenever I remembered to, and I practiced a lot of Yin Yoga while we were TTC (trying to conceive). My workouts are so intense that I really do need those 90 minutes to devote to stretching and relaxing. Yin also focusses a lot on hips: "Some experts also believe that specific poses can help promote baby-making by increasing blood flow to your pelvis, stimulating hormone-producing glands, and releasing muscle tension." - Parents.com Couldn't hurt, right? I swear, it helped! Within a week of practicing Yin I noticed a change in my cervical mucous and though we didn't conceived right away, I do think it sped along the process.