Causes of oral thrush in babies
Oral thrush is caused by a yeast fungus called Candida albicans.
Healthy people have this fungus in their mouths and it doesn't normally cause problems. But it can overgrow and infect the membranes in the mouth.
Babies are at an increased risk of oral thrush because their immune systems haven't fully developed yet and are less able to resist infection.
This is particularly the case with babies born prematurely (before 37 weeks of pregnancy).
Oral thrush can also affect babies if they have recently been treated with antibiotics.
Antibiotics reduce the levels of healthy bacteria in your baby's mouth, which can allow fungus levels to increase.
If you're breastfeeding and have been taking antibiotics for an infection, the levels of healthy bacteria in your body can be affected.
This can also make you prone to a thrush infection that may then be passed to your baby during breastfeeding.