How do I prevent constipation in pregnancy?

I am 28 years old and I am pregnant for three months now. Perhaps a bit too late, but I have just started buying all those medical books concerning pregnancy and birth. Now I am interested in everything concerning my health, and my baby's health too. I heard that there might be some constipation problems too. How do I prevent constipation in pregnancy?

To be honest, there are so many things that could go wrong during pregnancy, the constipation does seem a little less dangerously. It is caused most likely because of the hormonal changes that the woman's body is going through during the pregnancy. For precaution use cereals, fruit and include light exercises. Drink plenty of water and take iron pills.