- Bronchiolitis
- Breastfeeding jaundice
- Breast milk jaundice
- Branched-chain amino acid metabolism disorder
- Bartter syndrome
- Baby vomiting
- Baby hiccups
- Baby bald spot
- Autumn diarrhea
- Atypical hemolytic uremic syndrome
- Angelman syndrome
- Adenovirus infection
- Adenoid hypertrophy
- Adenoid facies
- Acute tracheobronchitis
- Acute laryngitis in children