Hi!
Congrats on your great news!!! As a former swimmer, high school coach, masters coach and two time mom myself, I can tell you from experience that it is GREAT to swim while pregnant! It's one of the best things you can do... and if you are one of the ladies who gets back problems, it's probably the BEST thing you can do because the water supports your belly and takes all the stress off your body... relaxing... and it feels so wonderful!!! The big thing to remember is that when you do breath control sets, don't go more than 5 or 7 strokes without breathing. Don't do the hypoxic (no breathers) 25's. You're breathing for two and by not breathing, you're depriving your baby of oxygen. So anytime you do those "no breathers", just breathe every 5 or 7 strokes instead. By the way, all four strokes are fine... none will hurt. My weak stroke is breaststroke, and my fellow coaches all said that the loosening of my joints must have been my problem, because my breaststroke improved while pregnant! :)
Hit the pool, sister! Enjoy!!!