Hyperophic pyloric stenosis presents after how many months of bih :

Pyloric stenosis is the most common surgical disorder producing emesis in infancy. It results from hyperophy of the circular and longitudinal muscularis of the pylorus and the distal antrum of the stomach with progressive narrowing of the pyloric canal. The cause is not known. The male-to-female incidence is 4:1.It presents 2-4 weeks after bih. Typically, the affected infant is full term when born and feeds and grows well until 2-4 weeks after bih, at which time occasional regurgitation of some of the feedings occurs. Ref :Albanese C.T., Sylvester K.G. (2010). Chapter 43. Pediatric Surgery. In G.M. Dohey (Ed), CURRENT Diagnosis & Treatment: Surgery, 13e.