It is totally normal for a pregnant woman to exercise during all the trimesters of her pregnancy. It builds internal strength and makes them healthy. Obviously you can not do vigorous workout as it may harm you and the baby, but simple workout is must. In fact, if you keep the workout at bay, your body would be stiff which is not good while you have delivery.
A lot of things need to be taken care of while doing workout. For example, your beat must not increase above 120 or the breathing pattern must be normal. Never over exert yourself and eat accordingly.
If you have been working out then it is easy for you to do workout during pregnancy. The one among favorites are aerobics, weight and breathing exercises. In case, you are a beginner and have not been working out then do it bit by bit. Do not rush and try to do everything in a single go. You can start up with basic aerobics and opt for weights later. Breathing exercise is so healthy that you can do it along with anything. The best time o exercise is early morning.
If you have back pain, then go for cardio exercises like walking and swimming. These are among the safest options for pregnant women. Do not do running, skipping or jogging as they may be risky. Do these for 15 minutes 4 times a week. Which ever exercise regimen you follow up during pregnancy, make sure to do it for 3 or 4 days in a week.
You may join yoga classes especially meant for pregnant women. This is a healthy way to to workout with minimum difficulty. It builds inner strength, releases pain (if any) and makes you feel fresh always. You can even join a dance class if you wish. This way you stay happy and get to stay fit at the same time.
Besides a good exercising routine, you must eat healthy and keep drinking loads of water and fruit juices. Have food stuff that has more of calcium, iron and proteins as it is essential for a healthy pregnancy.