Congrats if you are. I have 2 kids myself and have been able to get to my starting point within the year after. After the second it gets harder. Talk to your doctor if you are concerned. Stick to healthy foods and light exercise is actually good for you when you are pregnant. They have a lot on the web you should check it out! good luck.
There are workout tapes u can find on the net or in stores specifically for pregnancys. I know my favourite fitness expert brought out a tape when she was pregnant, so u can see here on their doing her thing big bump and all...im not sure what the forums rules are with posting shopping sites...but i found this for u
The best thing for staying in shape during pregnancy is walking. Walking is tjust right because it's not high impact and it works on the right muscles that you will need in shape for delivery. Walking at least 30 mins a day can keep you from gaining excess weight - ofcourse it's also very important to keep eating healthy foods, taking materna pills and keeping regular check ups with your obstitrician. Your doctor is the one to talk to before you assume anything though. And if you are pregnant - Congratulations!