Breastfed babies usually pass motion regularly as breast milk has enzymes and hormones that are suitable for digestion in an infant. Breast milk also provides a sufficient amount of fluids to the baby thus preventing dehydration and bulk for stools to be formed and passed easily. A baby can suck whatever quantity is needed to fulfill requirement of food as well as water. Thus breastfed babies have this advantage over bottle fed babies. 

However a baby’s bowel movements may vary from one to another and take time to establish like other body functions e.g. sleep and wake cycle.  Some pass stool after every feed, whereas some poop at intervals of one day to two to three days. 

They may pass gas but not necessarily stool every day.  But if a baby cries while passing stool, keeps legs up, tummy feels hard and he cries when touched there, the stool passed is hard pellet like balls, it means that he is constipated and is sick due to it.

Rarely, diseases like hirschspring can cause constipation. Lactose intolerance mostly manifests as diarrhea but can cause constipation sometimes. 

 Moreover if a baby is constipated, he may have pain during defecation. At times the soft anal area may get hurt while passing hard stools. This sets up a vicious cycle where the infant may avoid passing stools. The anal region may get wounded adding to the pain and discomfort. 

Lightly massaging the baby’s stomach can stimulate bowel movements and he may pass stool with ease. Holding legs up and rolling the baby lightly on the sides also helps to facilitate bowel movements. Intake of water can be increased by giving the child boiled and cooled water. Now from four months onwards he can be  given soild foods  like porridge, vegetable and fruit purees. This will supply necessary fiber and also nutrition. Solids should be initiated in very small quantity and increased gradually. Give one item in a small quantity to begin with. If the infant tolerates it well, increase quantity gradually and then add another food item.

Glycerin suppositories are good to cure constipation in babies. Pushing thermometers rectally has also been advised as a method to help clear the bowel. But inserting a thermometer or any instrument for that matter carries risk of trauma including perforation as the body of a baby is very delicate and soft, hence, is best avoided. 

If the above measures fail or the baby seems to be in a lot of pain, it is advisable to consult a pediatrician immediately.