We never did rice cereal, it is actually one of the foods that can cause trouble with bowel movements because it is fortified with iron. I never really offered anything to prevent constipation, just a healthy range of food and thankfully my DD has never experienced constipation. Food that can be a bit binding are things like banana and too much white carbs/dairy. Things that can help are porridge, kiwi fruit, pear, prunes and most importantly; making sure breastmilk or formula is still the main source of nutrition. Providing a sippy cup of water during meal times can also be a good idea.