| ASD | Atrial septal defect |
| BMI | Body mass index |
| CH | Congenital hypothyroidism |
| CHD | Congenital heart defect |
| DS | Down syndrome |
| HDD | Hospital discharge database |
| OH | Overt hypothyroidism |
| RCDT | Registry of Congenital Defects of Tuscany |
| RRDT | Registry of Rare Diseases of Tuscany |
| SH | Subclinical hypothyroidism |
| T4 | Thyroxine |
| TSH | Thyroid-stimulating hormone |
| VSD | Ventricular septal defect |