There is a significant diference between bottlefed and breastfed babies. Brestfed babies tends to have looser stool than bottle fed babies. An infant normally has 3-7 stools and 6 wet diapers each day. If your child is less than four months older and is not having enough wet diapers or bowel movements each day, you may need to consult your physician. If he/she is four months and older and is able to eat solid food, you may try the following steps.
1. Feed him/her some prune sauce. You will need to decide the amount depends on the age and weight of your child.
2. Offer him/her 8 -16 oz of prune juice per day. Reduce the amount for infants.
3. eat more fruit and vegetables such as grapes and celeries.
4. Offer him a teaspoon of sesame oil per day or two times a day if constipation is severe. But it's not recommended for infants.
5. If constipation lasts for  4-5 days, you may try Castor oil which is available over the counter in pharmacy. It tastes awful but works quickly. Check with your doctor before giving it to your child.