Hi These are really good questions that you have asked. I am sure it will help a lot of mothers. I will provide a detailed answer to this. First thing that we have to realize is Mothers milk is best for babies till 6 months of age, it's a complete food for them and an absolute requirement for their normal growth and development. There is no formula food that can replace the role of mother's milk. It's not only a complete food but it is the first opportunity for mother and child to bond together, the child's first human relation which goes long way in his interpersonal development. Is it ok to top feed with formula milk? Yes, it's okay. But it must be prescribed by a doctor. If doctor thinks your baby is not getting enough weight then he will prescribe formula milk. How can mothers know if baby needs formula milk? One simple thing. Excessive crying. In most cases, other than any illnesses, babies cry only when they are hungry. So if the baby is crying a lot, chances are mothers milk is not sufficient for him. If you think so, don't immediately start the baby on formula feeds. Consult a doctor and let him check if there isn't any pathology involved in this. Remember crying is the only way that babies tell us that they are in discomfort. What kind of discomfort, to decide that, you must take help of a pediatrician. 2. Can I breast feed him more than 20 mins? A single session of 20mins to 30 mins is sufficient for baby. Understand that whatever milk you are feeding, is going in his stomach. And babies have a very small stomach (obviously) . If you feed him more, ultimately he will vomit, which can cause more problems than it solves. Moreover if he is feeding for 20 minutes or more, that means mother is producing enough milk. As babies start teething if they are not able to derive enough milk out of the breast. 3. How can I know if he is getting enough feed? Simple, crying . At early age babies sleep for 18 to 22 hours. If he is sleeping less or crying excessively, chances are that he is not getting enough feed. And that's the time to contact your pediatrician to evaluate and if required start a formula feed. All mothers should practice what is called "On DEMAND FEEDING" . Whenever baby wants milk, be sure to be available to him. I will add another question to this answer, as most patients ask this. 4. Which one is best top feed to give to the child? Ans. Most top feeds contain almost similar contents, barring a few. Your pediatrician will conduct tests and accordingly will prescribe the best top feed for your baby. Follow up regularly with your doctor to know if they want to change the top feed. As while one top feed maybe good enough for the baby for say 3 months, but then it may require change to the other product. So visit your pediatrician regularly, sometimes just for a general checkup to make sure baby's growth and developmental milestones are normal and if he wants to supplement something. Choose to breast feed exclusively for 6 months.