It is some time called as failure to thrive and it can be a manifestation of medical conditions, social or environmental factors. The common symptoms are frequent crying, fussiness, missed milestones like not rolling over, sitting or walking. The common causes are premature birth, poor nutrition due to inadequate breastfeeding or inability to breastfeed, interference with child’s food access or ability to digest food, gastric reflux, or diarrhoea. Treatment depends on identifying and treating root cause of slow weight gain.