Pyloric stenosis is a condition where the opening between the stomach and small intestine narrows, preventing food from passing through. This impedes normal stomach emptying. It affects approximately 3% of newborns. The risk of developing pyloric stenosis increases significantly to about 20% if there is a family history of the condition. Importantly, most affected infants do not exhibit symptoms immediately after birth, with signs typically emerging around 4-5 weeks of age.