If you feel like doing abdominal crunches during your first trimester, before you have developed a baby bump, good for you! Doing abdominal work outs will not only help improve your stamina during labor and birth, but will also make it easier for your body to return to its pre-pregnancy shape. If you have the energy to run a marathon in your first trimester, there is absolutely no indication that this could negatively affect your fetus in any way. If you don't feel like working out, and prefer to relax, nobody will blame you for that either, though. As your pregnancy goes on, and you start "showing", abdominal exercises will become physically impossible. The body really is a wonderful thing you don't need your Great Aunt Katie-Jo or the person behind you in the line at Target to tell you that you should really not be doing ab crunches past your first trimester. Once you get there, you'll understand there this is not even theoretically possible. But, before that time arrives, enjoy your work outs without worrying!
Have you ever heard someone say that working out during pregnancy is not safe? You would certainly not be the only one. I love exercising. It makes me feel healthy and fit. For me, it also helps combat early pregnancy fatigue and even morning sickness. But it is easy to get worried about the safety of exercise during pregnancy if everyone keeps telling you that you have got to take it easy and put your feet up, "for the sake of the baby". If you are in your first trimester, your body is certainly working very hard on sustaining your new pregnancy. But your baby is tiny at this point, and your uterus has not yet expanded. You might be in the middle of morning sickness, and will be feeling very pregnant. But your pregnancy has not yet affected the shape and size of your body, and exercising is absolutely safe.