Congenital conditions are differences affecting body structure or function which are present from birth.

They are the result of a variation in the process of development of a baby in the womb.

There are many different types of congenital conditions, for example: 

• cleft lip and palate (external website)
• congenital heart disease(external website)
• Down syndrome (trisomy 21) (external website)

Most babies with a congenital condition will have a single condition.

Some can have multiple conditions as part of a recognised syndrome.

Many congenital conditions are rare diseases, affecting fewer than 1 in 2000 people.

What causes congenital conditions?

There are many causes of congenital conditions.

Some conditions are caused by an underlying genetic variation such as:

• the number or structure of a baby’s chromosomes
• a variation in a single gene

Others are the result of environmental factors that affect a baby’s development such as exposure to certain infections, medications, chemicals or poor nutrition.

Many conditions have no known cause and are assumed to be the result of the interplay between many genes and environmental factors.

Conditions may be identified during pregnancy, at birth or only as a baby grows older.

Some conditions can be identified through the pregnancy and newborn screening programmes (external website).​​