Birth Defects: Causes and Statistics (2023)

Every year, about 7.9 million infants (6% of worldwide births) are born with serious birth defects. With the causes of over 50% of birth defects unknown, how do we diagnose and prevent them?

Every year, an estimated 7.9 million infants (6% of worldwide births) are born with serious birth defects. Although some congenital defects can be controlled and treated, an estimated 3.2 million of these children are disabled for life. Moreover, birth defects are the leading cause of infant mortality in the United States. But where do these defects come from? Although some birth defects are inherited, others are a product of harmful environmental factors known as teratogens, and still others are multifactorial, resulting from a complex interaction of genetic and environmental influences. However, in approximately half of all birth defect cases, the causes are unknown (Christianson et al., 2006).

Genetic causes of birth defects fall into three general categories: chromosomal abnormalities, single-gene defects, and multifactorial influences. Prenatal environment can play a major role in the development of defects in all three categories, especially those linked to multifactorial causes.

Chromosomal Abnormalities

A person's genetic makeup is determined at conception. It is then, during the nuclear events of fertilization, that the genetic causes of many birth defects are determined. For example, chromosomal abnormalities, or large-scale duplications or deletions of chromosomal segments or entire chromosomes, can become apparent during this period. Many zygotes that carry such abnormalities do not develop into embryos, but among those that are carried to term, trisomy 21 (Down syndrome), trisomy 13 (Patau syndrome), and trisomy 18 (Edwards syndrome) are the most frequent birth defects. Embryos with these three conditions will develop severe disabilities regardless of the environmental factors associated with the pregnancy.

Unlike Down syndrome patients, who usually have a relatively long life span, children with Patau and Edwards syndromes often die soon after birth (March of Dimes, 2006). Individuals diagnosed with Patau syndrome suffer from neurological problems, mental and motor deficiencies, and polydactyly (Figure 1), as well as eye, heart, and spine defects (Patau et al., 1960). Those born with Edwards syndrome suffer mental retardation, breathing and feeding difficulties, delayed growth, and malformations of the kidneys, intestines, and heart (Edwards et al., 1960; Van Dyke & Allen, 1990). Thankfully, both of these devastating syndromes are rare.

Birth Defects: Causes and Statistics (3)

Figure 2:Primary Down syndrome is caused by the presence of three copies of chromosome 21.

(a) A child who has Down syndrome. (b) Idiogram of a person who has primary Down syndrome.

(a) © 2006 iStock.com/JSCook. (b) National Institutes of Health.

(Video) Preventing birth defects

Down syndrome, on the other hand, is by far the most common chromosomal abnormality, affecting 1 in 800 babies. The risk of having a child with this condition increases with maternal age, rising exponentially after a woman reaches age 35. For instance, in young mothers, the frequency of trisomy 21 is about 1 in 2,000, but this frequency rises to 1 in 100 when a woman is 40 and to 1 in 12 when she is 50 years old (Figure 2). People who have Down syndrome suffer from moderate to severe mental retardation and a wide variety of health problems, including heart defects, leukemia, and Alzheimer's disease. The severity of these defects varies widely, however, and the majority of people with Down syndrome live semi-independent lives, with an average life expectancy of 56 in the United States (Eyman et al., 1991). Aneuploidies such as Down syndrome can generally be detected by the presence of additional chromosomes or chromosome translocations in a karyotype or FISH profile.

(Video) Understanding the Causes of Major Birth Defects: Steps to Prevention

Single-Gene Defects

As opposed to chromosomal abnormalities, single-gene defects are usually inherited. For example, phenylketonuria (PKU) is a heritable condition caused by the malfunction of the PAH enzyme that breaks down the amino acid phenylalanine. Because this enzyme is coded for by the PAH gene on chromosome 12, PKU falls under the category of single-gene defects.

Interestingly, many single-gene defects are variably prevalent among different racial and ethnic groups. For instance, sickle-cell anemia (a disorder of the hemoglobin) is most common among people of African, Indian, and Mediterranean descent, whereas Tay-Sachs and Sandhoff diseases (both of which affect the nervous system) occur most frequently among Ashkenazi Jews. Tay-Sachs and Sandhoff diseases are both caused by a lack of the protein hexosaminidase, which controls the levels of fatty buildup in the brain. Specifically, autosomal recessive mutations in the HEXA gene on chromosome 15 cause various forms of Tay-Sachs, while the presence of a mutated HEXB gene on chromosome 5 causes Sandhoff. These disorders mainly affect young children, who typically die during the first few years of life from progressive neural degeneration.

Multifactorial Influences

In certain cases, a combination of genetic mutations and teratogens leads to the development of multifactorial birth defects. Although the exact causes of most multifactorial disorders are poorly understood, doctors can often identify common trends among similar conditions. Folate deficiency, for example, appears to play a role in various malformations of the neural tube, but the cumulative causes of such malformations and their relative contribution are rather complex. Neural tube defects have also been linked to trisomy 18, numerous mutations in the genes necessary for the development of the nervous system, and exposure to certain epilepsy drugs. Of the different forms of neural tube defects, a condition known as anencephaly is arguably the most severe. Anencephalic babies lack most of their brain and are often stillborn or die soon after birth. Spina bifida is a (relatively) less severe defect of the neural tube characterized by a series of deformities that are associated with incomplete enclosure of the spinal cord by the twenty-eighth day of development. The exposed spinal cord and the surrounding tissues are usually sealed surgically soon after birth, but the neurological effects, including partial paralysis and loss of bladder control, often last a lifetime.

Of course, not all birth defects have such profound consequences. Consider, for example, cleft lip and palate; this is a multifactorial birth defect that, if left uncorrected, can create difficulties with eating and speech. Children born with cleft lip usually undergo corrective surgery at an early age. Although genes definitely play a role in the development of this defect, environmental factors, including smoking and the use of antiseizure drugs, have been associated with a greater risk of bearing a child with cleft lip and/or palate (Ericson et al., 1979; Knight & Rhind, 1975).

(Video) Birth Defects: Awareness, Data, and Statistics

Prenatal Environment

It is difficult to overemphasize the importance of prenatal environment to a developing fetus. Indeed, a pregnant mother's health, diet, and level of exposure to toxins and environmental pollutants all have a direct effect on fetal development. For example, one of the most highly publicized cases of widespread toxin exposure associated with a pronounced increase in birth defects involves the use of Agent Orange, an herbicide that contains the poison dioxin, by the U.S. Army during the Vietnam War. Since the end of that conflict, the frequency of birth defects in those areas exposed to dioxin has risen to almost three times the norm. Dioxin, a product of industrial processes, disrupts the function of nuclear receptors and interferes with cell signaling. Moreover, dioxin is fat soluble and takes a long time to degrade, which means it can build up over time in soil, in water, and in the fatty tissue of animals that humans consume.

Other environmental toxins that might harm a fetus are taken voluntarily, such as drugs, alcohol, and cigarettes. For instance, excessive maternal alcohol consumption often causes fetal alcohol syndrome, which is characterized by defects of major organs, abnormal facial features, and mental retardation. Similarly, smoking during pregnancy has been linked to an increased risk of stillbirths, low birth weights, and cleft lip and/or palate (Ericson et al., 1979; Knight & Rhind, 1975). Although studies have not demonstrated a strong correlative link between a high incidence of birth defects and consumption of moderate amounts of alcohol and tobacco, doctors strongly recommend complete abstinence from smoking and drinking during pregnancy.

Yet another major factor linked to abnormal prenatal development is poor diet during pregnancy. Certain foods, such as seafood with high mercury content, should be consumed in moderation, whereas other high-vitamin foods are encouraged. Dietary supplements, such as folate (vitamin B9) and iodine taken before and during the early stages of pregnancy, can aid in development of the neural tube. It is important to understand, however, that good diet and a healthy lifestyle do not ensure a healthy child, although they do play a protective role in certain individuals.

(Video) Infections and Birth Defects (NIH, 1966)

Limiting the Frequency of Birth Defects

Although some congenital defects cannot be prevented, improvements in health care, nutrition, and education can reduce their frequency and phenotypic severity. The increasing use of prenatal genetic screens and preimplantation genetic diagnosis (PGD) is also helping limit the frequency and the severity of birth defects. These advances are a great tool, but they also have a surprising downside. Specifically, deleterious genetic mutations that have a recessive pattern of inheritance will remain in the population if the parents seeking PGD are allowed to select only healthy embryos to be carried to term. The current use of this technique, however, is limited to the select few who can afford it, so this phenomenon will not have a noticeable impact on the overall population for quite some time.

References and Recommended Reading

Christianson, A., et al. March of Dimes Global Report of Birth Defects: The Hidden Toll of Dying and Disabled Children. (2006) (accessed August 28, 2008).

Edwards, J. H., et al. A new trisomic syndrome. Lancet 1, 787–790 (1960)

Ericson, A., et al. Cigarette smoking as an etiologic factor in cleft lip and palate. American Journal of Obstetrics and Gynecology 135, 348–351 (1979)

Eyman, R. K., et al. Life expectancy of persons with Down syndrome. American Journal of Mental Retardation 95, 603–612 (1991)

Knight, A. H., & Rhind, E. G. Epilepsy and pregnancy: A study of 153 pregnancies in 59 patients. Epilepsia 16, 99–110 (1979)

Korkko, J., et al. Widely distributed mutations in the COL2A1 gene produce achondrogenesis type II/hypochondrogenesis. American Journal of Medical Genetics 92, 95–100 (2000)

March of Dimes. Chromosomal abnormalities. (2006) (accessed Aug. 28, 2008)

Patau, K., et al. Multiple congenital anomaly caused by an extra autosome. Lancet 1, 790–793 (1960)

Van Dyke, D. C., & Allen, M. Clinical management considerations in long-term survivors with trisomy 18. Pediatrics 85, 753–759 (1990).

(Video) Birth Defects: The Role of Research

FAQs

What are the 4 main causes of birth defects? ›

Smoking, drinking alcohol, or taking certain drugs during pregnancy. Having certain medical conditions, such as being obese or having uncontrolled diabetes before and during pregnancy. Taking certain medications, such as isotretinoin (a drug used to treat severe acne). Having someone in your family with a birth defect.

What are the statistics of birth defects? ›

Every 4 1/2 minutes, a baby is born with a birth defect in the United States. Birth defects affect 1 in every 33 babies born in the United States each year.

Does stress cause birth defects? ›

Stress results in increased catecholamine production, which in turn leads to decreased uterine blood flow and increased fetal hypoxia. Animal studies indicate that hypoxia affects a variety of developmental processes (eg, cell death)29 and organ systems, which could result in various types of birth defects.

What are the odds of having a healthy baby? ›

Reality Check: About 97 of every 100 babies born in the U.S. arrive without a major birth defect, such as spina bifida or Down syndrome.

Can sperm cause birth defects? ›

SUMMARY ANSWER. Among men undergoing infertility evaluation, there is no significant relationship between semen parameters and defect rates in live or still births, even when considering mode of conception.

What country has the most birth defects? ›

According to the report, Sudan has the most birth defects, with 82 per 1,000 live births, compared with 39.7 in France, which had the lowest number among the 193 countries surveyed.

When do most birth defects occur? ›

Birth defects can happen at any time during pregnancy. But most happen during the first 3 months of pregnancy (also called first trimester), when your baby's organs are forming. Birth defects also can happen later in pregnancy, when your baby's organs are still growing and developing.

Who is at risk for birth defects? ›

Risk increases under any of the following conditions: family history of birth defects or other genetic disorders. drug use, alcohol consumption, or smoking during pregnancy. maternal age of 35 years or older.

What is the most common genetic birth defect? ›

Down syndrome, on the other hand, is by far the most common chromosomal abnormality, affecting 1 in 800 babies. The risk of having a child with this condition increases with maternal age, rising exponentially after a woman reaches age 35.

Which birth defects are genetic? ›

Genetic Disorders and Defects
  • Angelman Syndrome. ...
  • Biotinidase Deficiency. ...
  • Birth Defects. ...
  • Carpenter Syndrome. ...
  • Cleft Lip/Cleft Palate. ...
  • Cloverleaf Deformity. ...
  • Clubbed Foot. ...
  • Craniofacial Disorder.

Can yelling cause birth defects? ›

“Although verbal abuse is often considered to be not as severe as physical abuse because it does not leave visible injuries, our findings suggest that verbal abuse can have major negative effects on newborn auditory function and development,” it concluded.

Does anger during pregnancy affect the baby? ›

In a follow-up across pregnancy, the fetuses of the high-anger women were noted to be more active and to experience growth delays. The high-anger mothers' high prenatal cortisol and adrenaline and low dopamine and serotonin levels were mimicked by their neonates' high cortisol and low dopamine levels.

Can arguing during pregnancy harm the baby? ›

Researchers at the Kochi Medical School in Japan found that verbal abuse from a significant other during pregnancy is linked to an increased risk of a baby being born with hearing problems.

What foods prevent Down syndrome? ›

Preventing Birth Defects
  • Take a vitamin with 400 micrograms of folic acid every day. ...
  • Foods with folic acid include : okra, pinto beans, navy beans, mustard green s, kale, spinach, chicken liver, beef liver, orange juice, asparagus, broccoli, avocado, green peas, cauliflower, tomato juice, peanuts, and cantaloupe.

What vitamins prevent birth defects? ›

CDC urges all women of reproductive age to take 400 micrograms (mcg) of folic acid each day, in addition to consuming food with folate from a varied diet, to help prevent some major birth defects of the baby's brain (anencephaly) and spine (spina bifida).

What makes you high risk for Down's syndrome baby? ›

Women who are 35 years or older when they become pregnant are more likely to have a pregnancy affected by Down syndrome than women who become pregnant at a younger age.3-5However, the majority of babies with Down syndrome are born to mothers less than 35 years old, because there are many more births among younger women ...

How can I make sure my baby is born healthy? ›

Increase their daily intake of folic acid (one of the B vitamins) to at least 400 micrograms. Make sure their immunizations are up to date. Control their diabetes and other medical conditions. Avoid smoking, drinking, and drug use.

Is it OK to conceive at 38? ›

After age 35, there's a higher risk of pregnancy-related complications that might lead to a C-section delivery. The risk of chromosomal conditions is higher. Babies born to older mothers have a higher risk of certain chromosomal conditions, such as Down syndrome. The risk of pregnancy loss is higher.

How is Down syndrome prevented? ›

There's no way to prevent Down syndrome. If you're at high risk of having a child with Down syndrome or you already have one child with Down syndrome, you may want to consult a genetic counselor before becoming pregnant. A genetic counselor can help you understand your chances of having a child with Down syndrome.

What birth defects come from the father? ›

Some studies have linked increasing paternal age (over 40 or so years) with higher rates of conditions like autism and schizophrenia. Others have observed increased rates of birth abnormalities, such as heart defects, musculoskeletal abnormalities, and Down's syndrome.

Does poor sperm quality affect baby? ›

The answer is yes. For instance, we know that sperm helps to determine how well the placenta forms — a key factor in fetal development — and that impaired sperm dramatically increases the likelihood of miscarriage, possibly because it is known to contain high levels of free radicals.

Does Dad's age affect baby? ›

A recent study of more than 40.5 million births in the United States revealed potentially harmful effects of advanced paternal age on a baby's risk of prematurity, low birth weight, low Apgar score and risk of seizures, as well as the mother's chances of developing gestational diabetes.

What ethnic group has the highest rate of birth defects? ›

A report by the Centers for Disease Control and Prevention (CDC) found that infant deaths related to birth defects were: 34 percent higher for babies of non-Hispanic black mothers than for babies of non-Hispanic white mothers. 26 percent higher for babies of Hispanic mothers than for babies of white mothers.

Are birth defects increasing? ›

The latest report from the Centers for Disease Control and Prevention finds that the number of cases of the birth defect nearly doubled from 1995 to 2005. The problem has continued to increase since 2005 for babies born to mothers of every race and age group.

How can you prevent chromosomal abnormalities during pregnancy? ›

Folic acid helps to prevent major birth defects of the brain and spine, specifically spina bifida. If there isn't enough of this circulating in a woman's body during the early weeks of pregnancy—before she even knows she's pregnant—then there is a higher chance the baby could have these types of defects.

How does a baby get a birth defect? ›

A birth defect is something visibly abnormal, internally abnormal, or chemically abnormal about your newborn baby's body. The defect might be caused by genetics, infection, radiation, or drug exposure, or there might be no known reason.

Which is the most critical month in pregnancy? ›

First Trimester (0 to 13 Weeks)

The first trimester is the most crucial to your baby's development. During this period, your baby's body structure and organ systems develop. Most miscarriages and birth defects occur during this period. Your body also undergoes major changes during the first trimester.

Why 8th month is critical in pregnancy? ›

The full development of your baby's brain and other vital organs such as lungs, eyes, heart, immune system, intestinal system, and kidneys takes place in this final term of your pregnancy.

Does lack of vitamin A cause birth defects? ›

Recently, a study in rats showed that dietary vitamin A deficiency two weeks before and during pregnancy can result in anorectal malformations and that the development of the enteric nervous system may be affected by the pathological changes involved in these malformations [92].

How can I prevent birth defects after 35? ›

Get early and regular prenatal care. Take prenatal vitamins every day that contain 0.4 milligrams of folic acid, which can help prevent certain birth defects. Start at least 2 months prior to conception. Eat a healthy, well-balanced diet that includes a variety of foods.

Which disorders are inherited from mother only? ›

The correct option is D Mitochondrial

_____ disorders are inherited from the mother only. Q. Why is mitochondrial DNA inherited only from mother?

What genes are inherited from father only? ›

#2 Y-Linked Traits (for Sons)

Sons can only inherit a Y chromosome from dad, which means all traits that are only found on the Y chromosome come from dad, not mom. Background: All men inherit a Y chromosome from their father, and all fathers pass down a Y chromosome to their sons.

What percentage of babies are born with defects? ›

CDC estimates that birth defects occur in about 1 in every 33 infants born in the United States each year. Birth defects can occur during any pregnancy, but some factors increase the risk for birth defects.

When do most birth defects occur? ›

Birth defects can happen at any time during pregnancy. But most happen during the first 3 months of pregnancy (also called first trimester), when your baby's organs are forming. Birth defects also can happen later in pregnancy, when your baby's organs are still growing and developing.

What are the signs of abnormal baby? ›

What are the symptoms of birth defects in a child?
  • Abnormal shape of head, eyes, ears, mouth, or face.
  • Abnormal shape of hands, feet, or limbs.
  • Trouble feeding.
  • Slow growth.
  • Frequent infections.
  • Joint problems.
  • Spinal cord not fully enclosed (spina bifida)
  • Kidney problems.

Can sperm cause birth defects? ›

SUMMARY ANSWER. Among men undergoing infertility evaluation, there is no significant relationship between semen parameters and defect rates in live or still births, even when considering mode of conception.

What is the most common genetic birth defect? ›

Down syndrome, on the other hand, is by far the most common chromosomal abnormality, affecting 1 in 800 babies. The risk of having a child with this condition increases with maternal age, rising exponentially after a woman reaches age 35.

What are the odds of having a healthy baby? ›

Reality Check: About 97 of every 100 babies born in the U.S. arrive without a major birth defect, such as spina bifida or Down syndrome.

Who is at risk for birth defects? ›

Risk increases under any of the following conditions: family history of birth defects or other genetic disorders. drug use, alcohol consumption, or smoking during pregnancy. maternal age of 35 years or older.

What country has the most birth defects? ›

According to the report, Sudan has the most birth defects, with 82 per 1,000 live births, compared with 39.7 in France, which had the lowest number among the 193 countries surveyed.

What is a butterfly baby? ›

Epidermolysis bullosa is a rare genetic condition that makes skin so fragile that it can tear or blister at the slightest touch. Children born with it are often called “Butterfly Children” because their skin seems as fragile as a butterfly wing. Mild forms may get better with time.

What is a golden baby? ›

Here are a couple other terms related to loss: angel baby: a baby that passes away, either during pregnancy or shortly after. born sleeping: a stillborn baby. golden baby or pot of gold: a baby born after a rainbow baby. sunset baby: a twin who dies in the womb.

What is a unicorn baby? ›

Babies who wake up every 2 hours to feed for weeks and weeks

Waking every 1-4 hours is much more common than babies who sleep 8 hours a night from birth (I like to call these super sleepers "unicorn babies" - I have heard of them, but have never experienced one myself).

What birth defects come from the father? ›

Some studies have linked increasing paternal age (over 40 or so years) with higher rates of conditions like autism and schizophrenia. Others have observed increased rates of birth abnormalities, such as heart defects, musculoskeletal abnormalities, and Down's syndrome.

Does poor sperm quality affect baby? ›

The answer is yes. For instance, we know that sperm helps to determine how well the placenta forms — a key factor in fetal development — and that impaired sperm dramatically increases the likelihood of miscarriage, possibly because it is known to contain high levels of free radicals.

Does Dad's age affect baby? ›

A recent study of more than 40.5 million births in the United States revealed potentially harmful effects of advanced paternal age on a baby's risk of prematurity, low birth weight, low Apgar score and risk of seizures, as well as the mother's chances of developing gestational diabetes.

Which disorders are inherited from mother only? ›

The correct option is D Mitochondrial

_____ disorders are inherited from the mother only. Q. Why is mitochondrial DNA inherited only from mother?

What genes are inherited from father only? ›

#2 Y-Linked Traits (for Sons)

Sons can only inherit a Y chromosome from dad, which means all traits that are only found on the Y chromosome come from dad, not mom. Background: All men inherit a Y chromosome from their father, and all fathers pass down a Y chromosome to their sons.

How are most birth defects caused? ›

Experts don't know the exact cause of most birth defects, but some reasons are: Genetic or hereditary factors. Infection during pregnancy. Drug exposure during pregnancy.

Videos

1. Genetic Birth Defects (Baby Health Guru)
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2. Thalidomide: The Chemistry Mistake That Killed Thousands of Babies
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3. Neural Tube Defects - Causes, Symptoms and Treatments and More
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4. Fetal Alcohol Syndrome, Causes, Signs and Symptoms, Diagnosis and Treatment.
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5. Teratogenic Causes of Birth Defects
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6. Zika Virus Causes the Brain Birth Defect CDC Confirms
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