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Home / Topic / Birth Defects / Types of Birth Defects Last Edited:
Wed Jul 15 12:52:46 EDT 2015

Types of Birth Defects

A baby may be born with a birth defect caused by a problem in his or her chromosomes, metabolism, formation of external body parts (such as limbs) or internal organs, or all three. On this website, we are only focusing on a limited set of  chromosomal  and  structural  defects.  Below is a table that lists the birth defects for which this website has information.  They are categorized by which area of the body is affected by the defect.

Chromosome

Chromosomes are the structures in cells that carry a personís genetic material, or DNA.  Chromosomal defects can occur in several forms. Infants may be born with too many or too few chromosomes. Chromosomal abnormalities may also occur when parts of chromosomes are broken or rearranged. These defects may happen when an egg or sperm cell is developing.

Down Syndrome (Trisomy 21)

Chromosomes are the structures in cells that carry a personís genetic material, or DNA.  Chromosomal defects can occur in several forms. Infants may be born with too many or too few chromosomes. Chromosomal abnormalities may also occur when parts of chromosomes are broken or rearranged. These defects may happen when an egg or sperm cell is developing.

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Face

ORAL-FACIAL CLEFTS

Oral-facial clefts occur when the structures that form an infantís lip and/or mouth do not completely fuse during development. Clefts can range in size and severity. Oral-facial clefts affect about 6,800 infants per year in the United States.

Clefts are divided into two conditions: cleft lip (with or without cleft palate) and cleft palate (without cleft lip).

More information and resources can be found on the California Birth Defects Monitoring Program's Cleft Lip / Cleft Palate Fact Sheet (PDF).  

Cleft Lip (with or without cleft palate)

ORAL-FACIAL CLEFTS

Oral-facial clefts occur when the structures that form an infantís lip and/or mouth do not completely fuse during development. Clefts can range in size and severity. Oral-facial clefts affect about 6,800 infants per year in the United States.

Clefts are divided into two conditions: cleft lip (with or without cleft palate) and cleft palate (without cleft lip).

More information and resources can be found on the California Birth Defects Monitoring Program's Cleft Lip / Cleft Palate Fact Sheet (PDF).  

Cleft Palate (without cleft lip)

ORAL-FACIAL CLEFTS

Oral-facial clefts occur when the structures that form an infantís lip and/or mouth do not completely fuse during development. Clefts can range in size and severity. Oral-facial clefts affect about 6,800 infants per year in the United States.

Clefts are divided into two conditions: cleft lip (with or without cleft palate) and cleft palate (without cleft lip).

More information and resources can be found on the California Birth Defects Monitoring Program's Cleft Lip / Cleft Palate Fact Sheet (PDF).  

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Brain and Spinal Cord

NEURAL TUBE DEFECTS

The neural tube is a narrow channel along the back of a developing embryo that folds and closes to form the brain and spinal cord.  It closes very early in pregnancy, often before a woman realizes she is pregnant.  When it does not close correctly, an infant is born with a neural tube birth defect. 

The causes of neural tube defects are not fully understood, and both genetic and environmental factors contribute to these defects.  Pregnant women are at risk for having a baby with a neural tube defect if they take certain anti-seizure medications, have poorly managed chronic conditions such as obesity or diabetes, or are deficient in folic acid.  Folic acid, in particular, can help prevent neural tube defects if taken before and during pregnancy.

A woman may be screened for neural tube defects during pregnancy through a prenatal blood test.  If the test indicates an increased risk for a neural tube defect in the fetus, she will be referred for genetic counseling, and detailed ultrasound and/or amniocentesis may rule out or confirm the diagnosis.

More information and resources can be found on the California Birth Defects Monitoring Program's Neural Tube Defects Fact Sheet (PDF), and the Genetic Disease Screening Program's Prenatal Screening website.

Anencephaly

NEURAL TUBE DEFECTS

The neural tube is a narrow channel along the back of a developing embryo that folds and closes to form the brain and spinal cord.  It closes very early in pregnancy, often before a woman realizes she is pregnant.  When it does not close correctly, an infant is born with a neural tube birth defect. 

The causes of neural tube defects are not fully understood, and both genetic and environmental factors contribute to these defects.  Pregnant women are at risk for having a baby with a neural tube defect if they take certain anti-seizure medications, have poorly managed chronic conditions such as obesity or diabetes, or are deficient in folic acid.  Folic acid, in particular, can help prevent neural tube defects if taken before and during pregnancy.

A woman may be screened for neural tube defects during pregnancy through a prenatal blood test.  If the test indicates an increased risk for a neural tube defect in the fetus, she will be referred for genetic counseling, and detailed ultrasound and/or amniocentesis may rule out or confirm the diagnosis.

More information and resources can be found on the California Birth Defects Monitoring Program's Neural Tube Defects Fact Sheet (PDF), and the Genetic Disease Screening Program's Prenatal Screening website.

Spina Bifida

NEURAL TUBE DEFECTS

The neural tube is a narrow channel along the back of a developing embryo that folds and closes to form the brain and spinal cord.  It closes very early in pregnancy, often before a woman realizes she is pregnant.  When it does not close correctly, an infant is born with a neural tube birth defect. 

The causes of neural tube defects are not fully understood, and both genetic and environmental factors contribute to these defects.  Pregnant women are at risk for having a baby with a neural tube defect if they take certain anti-seizure medications, have poorly managed chronic conditions such as obesity or diabetes, or are deficient in folic acid.  Folic acid, in particular, can help prevent neural tube defects if taken before and during pregnancy.

A woman may be screened for neural tube defects during pregnancy through a prenatal blood test.  If the test indicates an increased risk for a neural tube defect in the fetus, she will be referred for genetic counseling, and detailed ultrasound and/or amniocentesis may rule out or confirm the diagnosis.

More information and resources can be found on the California Birth Defects Monitoring Program's Neural Tube Defects Fact Sheet (PDF), and the Genetic Disease Screening Program's Prenatal Screening website.

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Reproductive System

Hypospadias

This birth defect occurs in males when the opening of the urethra, the tube that carries urine from the bladder to the outside of the body, is located along the underside of the penis instead of at the tip.  This defect occurs when urethra does not complete its development during the pregnancy.

The exact cause of hypospadias is unknown.  However, research indicates that prenatal exposure to hormones such as progesterone and estrogen may increase the risk of hypospadias. 

The severity of this birth defect varies by location of the hypospadias.  In mild cases, the problem is cosmetic rather than causing any functional problem after birth.  When desired, surgery is usually performed when the infant is between 6 to 18 months old.

Hypospadias

Hypospadias

This birth defect occurs in males when the opening of the urethra, the tube that carries urine from the bladder to the outside of the body, is located along the underside of the penis instead of at the tip.  This defect occurs when urethra does not complete its development during the pregnancy.

The exact cause of hypospadias is unknown.  However, research indicates that prenatal exposure to hormones such as progesterone and estrogen may increase the risk of hypospadias. 

The severity of this birth defect varies by location of the hypospadias.  In mild cases, the problem is cosmetic rather than causing any functional problem after birth.  When desired, surgery is usually performed when the infant is between 6 to 18 months old.

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Heart

HEART DEFECTS

Heart defects are among the most common birth defects and are the leading cause of birth defect related deaths.  They may occur along with chromosomal birth defects such as Down Syndrome and Turner Syndrome.  Heart defects affect about 35,000 infants per year in the United States.

Heart defects develop in the early weeks of pregnancy when the heart is forming.  Heart defects may be detected prenatally using ultrasound (echocardiography), and medications might be prescribed to restore a normal heart rhythm.

However, most heart defects are usually diagnosed after birth by chest x-ray, electrocardiogram, and echocardiogram.  A heart abnormality seldom causes problems while the fetus is in the womb and may only become evident after birth.  Most infants diagnosed with major heart abnormalities undergo surgery within the first few months of life.  Small holes in the heart usually close without treatment.

Although the causes of most congenital heart defects are unknown, there are several environmental factors that may contribute to their occurrence.  Prenatal risk factors include:

  • Exposure to rubella (German measles), influenza, and other infections
  • Alcohol use
  • Cocaine use
  • Medications such as isotretinoin (Accutane) and some anti-seizure medications
  • Exposure to chemical solvents such paint, varnish, and some cleaning products

More information and resources can be found on the California Birth Defects Monitoring Program's Heart Defects Fact Sheet (PDF)

Hypoplastic Left Heart Syndrome

HEART DEFECTS

Heart defects are among the most common birth defects and are the leading cause of birth defect related deaths.  They may occur along with chromosomal birth defects such as Down Syndrome and Turner Syndrome.  Heart defects affect about 35,000 infants per year in the United States.

Heart defects develop in the early weeks of pregnancy when the heart is forming.  Heart defects may be detected prenatally using ultrasound (echocardiography), and medications might be prescribed to restore a normal heart rhythm.

However, most heart defects are usually diagnosed after birth by chest x-ray, electrocardiogram, and echocardiogram.  A heart abnormality seldom causes problems while the fetus is in the womb and may only become evident after birth.  Most infants diagnosed with major heart abnormalities undergo surgery within the first few months of life.  Small holes in the heart usually close without treatment.

Although the causes of most congenital heart defects are unknown, there are several environmental factors that may contribute to their occurrence.  Prenatal risk factors include:

  • Exposure to rubella (German measles), influenza, and other infections
  • Alcohol use
  • Cocaine use
  • Medications such as isotretinoin (Accutane) and some anti-seizure medications
  • Exposure to chemical solvents such paint, varnish, and some cleaning products

More information and resources can be found on the California Birth Defects Monitoring Program's Heart Defects Fact Sheet (PDF)

Tetralogy of Fallot

HEART DEFECTS

Heart defects are among the most common birth defects and are the leading cause of birth defect related deaths.  They may occur along with chromosomal birth defects such as Down Syndrome and Turner Syndrome.  Heart defects affect about 35,000 infants per year in the United States.

Heart defects develop in the early weeks of pregnancy when the heart is forming.  Heart defects may be detected prenatally using ultrasound (echocardiography), and medications might be prescribed to restore a normal heart rhythm.

However, most heart defects are usually diagnosed after birth by chest x-ray, electrocardiogram, and echocardiogram.  A heart abnormality seldom causes problems while the fetus is in the womb and may only become evident after birth.  Most infants diagnosed with major heart abnormalities undergo surgery within the first few months of life.  Small holes in the heart usually close without treatment.

Although the causes of most congenital heart defects are unknown, there are several environmental factors that may contribute to their occurrence.  Prenatal risk factors include:

  • Exposure to rubella (German measles), influenza, and other infections
  • Alcohol use
  • Cocaine use
  • Medications such as isotretinoin (Accutane) and some anti-seizure medications
  • Exposure to chemical solvents such paint, varnish, and some cleaning products

More information and resources can be found on the California Birth Defects Monitoring Program's Heart Defects Fact Sheet (PDF)

Transposition of the Great Arteries (Vessels)

HEART DEFECTS

Heart defects are among the most common birth defects and are the leading cause of birth defect related deaths.  They may occur along with chromosomal birth defects such as Down Syndrome and Turner Syndrome.  Heart defects affect about 35,000 infants per year in the United States.

Heart defects develop in the early weeks of pregnancy when the heart is forming.  Heart defects may be detected prenatally using ultrasound (echocardiography), and medications might be prescribed to restore a normal heart rhythm.

However, most heart defects are usually diagnosed after birth by chest x-ray, electrocardiogram, and echocardiogram.  A heart abnormality seldom causes problems while the fetus is in the womb and may only become evident after birth.  Most infants diagnosed with major heart abnormalities undergo surgery within the first few months of life.  Small holes in the heart usually close without treatment.

Although the causes of most congenital heart defects are unknown, there are several environmental factors that may contribute to their occurrence.  Prenatal risk factors include:

  • Exposure to rubella (German measles), influenza, and other infections
  • Alcohol use
  • Cocaine use
  • Medications such as isotretinoin (Accutane) and some anti-seizure medications
  • Exposure to chemical solvents such paint, varnish, and some cleaning products

More information and resources can be found on the California Birth Defects Monitoring Program's Heart Defects Fact Sheet (PDF)

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Intestines

Gastroschisis

Gastroschisis is a birth defect that occurs when a portion of the infantís intestines protrudes through the body, typically just next to the umbilical cord.  This defect can range in severity and size, and it can affect other organs such as the liver.  About 1,500 infants in the United States are born per year with this defect.  Surgical correction is required.

The causes of gastrochisis are still unknown.  Some research has shown that adolescent mothers or mothers who consume a high fat and high cholesterol diet may be more likely to give birth to an infant with gastrochisis.

Infants and children who have had gastrochisis may face challenges moving digested food through the stomach and intestines and absorbing nutrients.

More information and resources can be found on the California Birth Defects Monitoring Program's Gastroschisis Fact Sheet (PDF)

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Limbs

Affecting about 1,500 infants per year in the United States, a limb deficiency occurs when a part of one or both arms or legs fails to form completely during pregnancy.  The resulting limb is reduced from its normal size or is missing.  This condition is also known as a limb reduction defect.

The causes of limb deficiencies are not well understood.  Research suggests that some exposures during pregnancy may increase the risk of having an infant with a limb reduction defect.  Exposures that are being considered by researchers as potentially contributing to these defects include viruses, chemicals, medications, and tobacco smoke.

The severity of this birth defect depends on the location and size of the limb reduction.  Infants born with upper and/or lower limb deficiencies may face challenges with:

  • Motor skill development
  • Caring for oneself
  • Physical activity
  • Social and emotional issues

Treatment for limb deficiencies varies.  Potential treatments can include prosthetics (artificial limbs), orthotics (splints or braces), surgery, and/or rehabilitation (physical and occupational therapy). 

Upper Limb Deficiencies

Affecting about 1,500 infants per year in the United States, a limb deficiency occurs when a part of one or both arms or legs fails to form completely during pregnancy.  The resulting limb is reduced from its normal size or is missing.  This condition is also known as a limb reduction defect.

The causes of limb deficiencies are not well understood.  Research suggests that some exposures during pregnancy may increase the risk of having an infant with a limb reduction defect.  Exposures that are being considered by researchers as potentially contributing to these defects include viruses, chemicals, medications, and tobacco smoke.

The severity of this birth defect depends on the location and size of the limb reduction.  Infants born with upper and/or lower limb deficiencies may face challenges with:

  • Motor skill development
  • Caring for oneself
  • Physical activity
  • Social and emotional issues

Treatment for limb deficiencies varies.  Potential treatments can include prosthetics (artificial limbs), orthotics (splints or braces), surgery, and/or rehabilitation (physical and occupational therapy). 

Lower Limb Deficiencies

Affecting about 1,500 infants per year in the United States, a limb deficiency occurs when a part of one or both arms or legs fails to form completely during pregnancy.  The resulting limb is reduced from its normal size or is missing.  This condition is also known as a limb reduction defect.

The causes of limb deficiencies are not well understood.  Research suggests that some exposures during pregnancy may increase the risk of having an infant with a limb reduction defect.  Exposures that are being considered by researchers as potentially contributing to these defects include viruses, chemicals, medications, and tobacco smoke.

The severity of this birth defect depends on the location and size of the limb reduction.  Infants born with upper and/or lower limb deficiencies may face challenges with:

  • Motor skill development
  • Caring for oneself
  • Physical activity
  • Social and emotional issues

Treatment for limb deficiencies varies.  Potential treatments can include prosthetics (artificial limbs), orthotics (splints or braces), surgery, and/or rehabilitation (physical and occupational therapy). 

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