500 children aged 0-5 years followed since birth by Principal Investigator (PI)since January1, 2003 till December 31, 2018 and diagnosed with adenoid hypertrophy (AH) (study group) and 500 children aged 0-5 years followed by principal investigator during the same years and diagnosed as urinary tract infection (UTI), gastroenteritis (GE), diarrhea, vomiting but without AH (control group) were compared. Morbidity and treatment will be compared and correlated with gastro-esophageal reflux (GER), allergy and infant feeding position during the first few years of life in the two groups.

The 2 groups are children aged 0-5 years and treated by PI and followed since birth during years 2003-2018. Study group consists of children diagnosed at least 2 times as AH and control group as similar children with UTI, GE, vomiting or diarrhea. Respiratory problems (pneumonia, bronchopneumonia, bronchitis), ear problems (otitis media OM, serous OM), antibiotic treatment, use of bronchodilators, inhaled corticosteroid (ICS), chest X-rays, anomalous laboratory results, emergency room visits and hospitalization rates will be compared in the two groups, together with details concerning feeding position during the first years of life. Correlation between morbidity, degree of nasopharyngeal obstruction, allergy, GER and supine feeding position, will be evaluated.

Inclusion Criteria: Study group: Young children with diagnosis of adenoid hypertrophy followed by PI Control group: young children with diagnosis of UTI, GE, vomiting or diarrhea followed by PI

Exclusion Criteria: Children with cystic fibrosis, primary dyskinesia, immune deficiency, congenital anatomical malformations of nasal or airway passages.

Children older than 6 months of age when starting to be followed by PI.

Young infants followed since birth or from the first half of the first year of life, followed at least for 5 years by PI, study group (till 500 children) with the diagnosis of AH, control group (till 500 children) diagnosed as UTI, GE, vomiting or diarrhea and without AH.