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Birth Defects:  Frequently Asked Questions (FAQs)

Q:  What is a birth defect?

A birth defect is a problem that happens while the baby is developing in the mother’s body.  Most birth defects happen during the first 3 months of pregnancy.

A birth defect may affect how the body looks, works, or both.  It can be found before birth, at birth, or anytime after birth.  Most defects are found within the first year of life.  Some birth defects (such as cleft lip or clubfoot) are easy to see, but others (such as heart defects or hearing loss) are found using special tests (such as x-rays, CAT scans, or hearing tests).  Birth defects can vary from mild to severe.

Some birth defects can cause the baby to die.  Babies with birth defects may need surgery or other medical treatments, but, if they receive the help they need, these babies often lead full lives. 

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Q: What are the most common birth defects?

One of every 33 babies is born with a birth defect.  A birth defect can affect almost any part of the body.  The well being of the child depends mostly on which organ or body part is involved and how much it is affected.

Many birth defects affect the heart.  About 1 in every 100 to 200 babies is born with a heart defect.  Heart defects make up about one-third to one-fourth of all birth defects.  Some of these heart defects can be serious, and a few are very severe.  In some places of the world, heart defects cause half  of all deaths from birth defects in children less than 1 year of age.

Other common birth defects are “neural tube defects,” which are defects of the spine (spina bifida) and brain (anencephaly).  They affect about 1 of 1,000 pregnancies.  These defects can be serious and are often life threatening.  They happen less often than heart defects, but they cause many fetal and infant deaths.  

Birth defects of the lip and roof of the mouth are also common. These birth defects, known as “orofacial clefts,” include cleft lip, cleft palate, and combined cleft lip and cleft palate.  Cleft lip is more common than cleft palate.  In many places of the world, orofacial clefts affect about 1 in 700 to 1,000 babies.

Some birth defects are common but rarely life threatening, though they often require medical and surgical attention.  “Hypospadias,” for example, is a fairly common defect found in male babies.  In babies with hypospadias, the opening of the urethra (where urine comes out) is not at the tip of the penis but on the underside.  Treatment depends on how far away from the tip the opening is and can involve complex surgery.  This defect is rarely as serious as the others listed above, but it can cause great concern and sometimes has high medical costs.  It rarely causes death.

These are only some of the most common birth defects.  Two final points are worth noting.  First, genetic conditions, though not mentioned so far, also occur often.  Down syndrome, for example, is a genetic condition that affects about 1 in 800 babies, but it affects many more babies who are born to older women.  Second, a woman who is pregnant may miscarry a baby (fetus) early, before it is time for the baby to be born.  This often happens when the fetus has a severe birth defect.  To know the true impact of birth defects and how often they occur, we not only need to look at babies born but also, if possible, look at all pregnancies.

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Q: What is my chance of having a baby with a birth defect?

In the United States, about 3% of babies are born with birth defects.  Some women have a higher chance of having a child with a birth defect.  Women over the age of 35 years have a higher chance of having a child with Down syndrome than women who are younger.  If taken when a woman is pregnant, certain drugs can increase the chance of birth defects.  Also, women who smoke and use alcohol while pregnant have a higher risk of having a baby with certain birth defects.  Other women have a higher chance of having a baby with a birth defect because someone in their family had a similar birth defect.  To learn more about your risk of having a baby with a birth defect, you can talk with a genetic counselor.  (To find a genetic counselor, see Where can I find a geneticist or genetic counselor?Also, to reduce your chances of having a baby with a birth defect, talk with your health care provider about any medicines that you take, do not drink alcohol or smoke, and be sure to take 400 micrograms of the B vitamin folic acid every day.  It is the amount of folic acid found in most multivitamins.

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Q: Does my risk for having a baby with a birth defect increase as I get older?

Women who are 35 years of age or older have a greater chance of having a baby with Down syndrome.  Of the known causes of mental retardation, Down syndrome is the most common.  It affects about 1 in 800 births.  Down syndrome happens when there is an extra chromosome 21 (“trisomy 21”).  Scientists have not proven that other birth defects, genetic or otherwise, are linked to the mother’s age.  

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Normal chromosomes

Q: Do genetic factors play a role in causing birth defects?

Yes, some birth defects “run in the family.” Babies with certain types of birth defects may have an extra or a missing chromosome.  Birth defects can also happen when just a piece of a chromosome is missing or if just an extra piece is added.  Also, certain genes may make a fetus more sensitive to things that cause birth defects.  





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This page was last updated August 05, 2004

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National Center on Birth Defects and Developmental Disabilities

The National Center on Birth Defects and Developmental Disabilities (NCBDDD) promotes the health of babies, children, and adults, and enhances the potential for full, productive living.  Our work includes identifying the causes of birth defects and developmental disabilities, helping children to develop and reach their full potential, and promoting health and well-being among people of all ages with disabilities.