Birth defects, also known as congenital anomalies, are structural changes present at birth that affect the child’s development, function, and health. They can affect any body part and range dramatically in terms of their impact on the child’s wellbeing.
Some congenital disabilities, like cleft lip, can be easily repaired with surgery, while others, like anencephaly, are incompatible with life. Birth defects are the leading cause of infant mortality in the United States, accounting for approximately 20% of all infant mortality. Understanding the prevalence, types, causes, and preventative measures for birth defects is an important public health priority.
Specific Types of Birth Defects
There are a vast number of different congenital anomalies that have been identified. Some
of the most common categories include:
Brain and Spine Defects
Defects of the brain and spine are among the most serious congenital disorders. They can impair physical, cognitive, and neurological function. Common brain and spine defects include:
- Anencephaly – Partial absence of the brain and skull. Affects approximately 1 in 4,647 births or about 847 babies per year in the US.
- Encephalocele – Encephalocele is a rare neural tube defect in which the brain and membranes abnormally protrude through an opening in the skull caused by improper neural tube closure during early pregnancy. Prevalence is approximately 1 in 10,502 births, impacting around 375 infants annually in the US.
- Spina Bifida – Spina bifida is a condition that affects the spine and is usually apparent at birth. It is a type of neural tube defect. It occurs in about 1 in 2,758 births, affecting approximately 1,427 babies annually in the US. It can cause physical and intellectual disabilities.
Defects of eye development are also common congenital disorders:
- Anophthalmia/Microphthalmia – Partial or complete absence of one or both eyes. Prevalence is approximately 1 in 5,243 births, impacting around 751 infants per year in the US.
Congenital heart defects make up the most common category of birth defects. There are many different types of structural heart problems, some relatively minor and others requiring complex surgery:
- Atrioventricular septal defect – Hole between the atria and ventricles. Prevalence is approximately 1 in 1,859 births or 2,118 cases annually.
- Coarctation of the aorta – Narrowing of the aorta. It occurs in around 1 in 1,795 births, affecting approximately 2,194 infants per year.
- Hypoplastic left heart syndrome – Hypoplastic left heart syndrome (HLHS) is a birth defect that affects normal blood flow through the heart. Prevalence is approximately 1 in 3,841 births or 1,025 cases per year.
- Tetralogy of Fallot – Combination of four defects, including ventricular septal defect. It occurs in about 1 in 2,171 births or 1,813 cases annually.
- Transposition of the great arteries – Reversed position of the aorta and pulmonary artery. Prevalence is approximately 1 in 2,695 births per year.
Oral clefts are examples of defects affecting the face and mouth:
- Cleft lip with or without cleft palate – Opening in the upper lip with or without an opening in the roof of the mouth. Prevalence ranges from 1 in 1,563 to 1 in 2,807 births, affecting between 1,402-2,518 infants annually in the US.
- Cleft palate – Opening in the roof of the mouth. It occurs in about 1 in 1,687 births, impacting around 2,333 babies per year.
Two examples of congenital disabilities affecting the gastrointestinal system include:
- Esophageal atresia – Blocked or absent esophagus. Approximately 1 in 4,144 births or 950 cases per year in the US.
- Intestinal atresias – Blockage of the intestine. Prevalence is around 1 in 2,242 births, affecting approximately 1,756 infants annually.
Some common congenital anomalies affecting the muscles, bones, and limbs:
- Clubfoot – Foot twisted inward and upward. It occurs in about 1 in 593 births, impacting around 6,643 babies per year in the US.
- Diaphragmatic hernia – Hole in the diaphragm. Prevalence is approximately 1 in 3,591 births or 1,096 annual cases.
- Gastroschisis – The stomach and intestines protrude through a hole beside the belly button: approximately 1 in 1,953 births or 2,015 cases per year.
- Omphalocele – Intestines and organs protrude through the belly button. Prevalence is around 1 in 4,175 births, affecting 943 infants annually.
Errors in chromosomes and genes can lead to congenital conditions such as:
- Down syndrome (Trisomy 21) – Extra copy of chromosome 21. It occurs in approximately 1 in 707 births, impacting around 5,568 babies per year.
- Patau syndrome (Trisomy 13) and Trisomy 18 (Edwards syndrome) – Extra copies of chromosomes 13 and 18, respectively. Prevalence ranges from 1 in 3,315 to 1 in 7,409 births annually.
Factors That Cause Birth Defects
A number of factors can increase the risk for certain birth defects:
- Advanced maternal and paternal age – Risk increases with the age of both parents.
- Exposure to teratogens – Substances like alcohol, tobacco, infections and certain medications can disrupt fetal development when exposed during pregnancy.
- Chronic maternal health conditions – Diseases like obesity, diabetes, and epilepsy increase risk if not properly managed.
- Genetic and chromosomal abnormalities – Changes in chromosomes, genes or genetic inheritance can lead to birth defects.
- Nutritional factors – Insufficient intake of key nutrients like folic acid increases the risk for certain defects.