Birth defect: Difference between revisions

Revision as of 13:39, 19 March 2025

Congenital abnormalities present at birth

Birth defects are structural or functional abnormalities present at birth that can affect any part of the body, including organs, limbs, metabolism, and development. These defects can vary in severity, ranging from mild conditions that require little to no medical intervention to severe abnormalities that may cause disability or death. Birth defects can be genetic, environmental, or multifactorial in origin.

Epidemiology

Birth defects occur worldwide and are one of the leading causes of infant mortality and childhood disabilities. Some key epidemiological facts include:

Affect approximately 1 in 33 newborns worldwide.
Account for a significant percentage of infant deaths globally.
Can be detected prenatally, at birth, or later in life, depending on severity and type.

Causes of Birth Defects

Birth defects arise from a combination of genetic, environmental, and unknown factors. The major causes include:

Genetic Factors

Genetic birth defects occur due to mutations in DNA or chromosomal abnormalities. These may be inherited or result from spontaneous mutations.

Chromosomal disorders – Conditions such as Down syndrome (Trisomy 21), Turner syndrome, and Klinefelter syndrome.
Single-gene mutations – Conditions such as cystic fibrosis, sickle cell anemia, and Tay-Sachs disease.

Environmental Factors

Certain environmental factors can interfere with fetal development and lead to birth defects:

Teratogens – Substances that can cause birth defects, including:
Alcohol – Causes fetal alcohol spectrum disorders (FASD).
Drugs – Certain medications, including thalidomide, isotretinoin, and some anticonvulsants.
Infections – Congenital infections such as rubella, cytomegalovirus (CMV), toxoplasmosis, and syphilis.
Radiation – Exposure to high levels of radiation can lead to fetal malformations.
Tobacco and pollutants – Can increase the risk of low birth weight and congenital abnormalities.

Multifactorial Causes

Many birth defects result from a combination of genetic and environmental factors. Conditions such as neural tube defects (spina bifida, anencephaly) and congenital heart defects fall into this category.

Types of Birth Defects

Birth defects can be categorized based on their impact on different body systems:

Structural Birth Defects

Structural defects involve physical abnormalities in the body's formation:

Neural tube defects – Spina bifida, anencephaly, encephalocele.
Congenital heart defects – Tetralogy of Fallot, atrial septal defect, ventricular septal defect.
Cleft lip and cleft palate – Affects the mouth and facial structure.
Limb deformities – Clubfoot, missing or extra fingers (polydactyly, syndactyly).
Gastrointestinal defects – Hirschsprung's disease, gastroschisis, omphalocele.

Functional or Developmental Birth Defects

These defects impact organ function, metabolism, or brain development:

Metabolic disorders – Phenylketonuria (PKU), galactosemia, maple syrup urine disease.
Neurological disorders – Cerebral palsy, microcephaly, hydrocephalus.
Sensory impairments – Congenital hearing loss, blindness.
Endocrine disorders – Congenital hypothyroidism, adrenal hyperplasia.

Diagnosis

Birth defects can be diagnosed through prenatal screening, newborn screening, and physical examinations.

Prenatal Diagnosis

Ultrasound imaging – Detects physical abnormalities in fetal development.
Amniocentesis – Used to analyze genetic material for chromosomal disorders.
Chorionic villus sampling (CVS) – Early genetic testing for chromosomal abnormalities.
Maternal serum screening – Identifies markers for Down syndrome, trisomy 18, and neural tube defects.

Newborn Screening

Many countries conduct newborn screening for common metabolic and genetic conditions, such as:

Phenylketonuria (PKU)
Congenital hypothyroidism
Cystic fibrosis
Sickle cell disease

Postnatal Diagnosis

Some birth defects are not detected at birth and only become evident as the child grows. These include developmental delays, sensory impairments, and metabolic disorders.

Prevention

While not all birth defects are preventable, several strategies can reduce the risk:

Preconception and Prenatal Care

Folic acid supplementation – Reduces the risk of neural tube defects.
Avoidance of alcohol, smoking, and illicit drugs – Prevents fetal alcohol spectrum disorders and other defects.
Vaccination against infections (e.g., rubella) – Prevents congenital infections.
Managing chronic conditions (e.g., diabetes) – Helps control risks associated with pregnancy.
Avoiding harmful medications during pregnancy – Consult with a healthcare provider before taking any drugs.

Genetic Counseling

For individuals with a family history of birth defects, genetic counseling can provide:

Risk assessment for inherited conditions.
Options for prenatal genetic testing.
Reproductive planning strategies.

Treatment and Management

The management of birth defects depends on their type, severity, and impact on health. Some defects may require surgical correction, while others involve long-term medical care.

Surgical Interventions

Many structural birth defects can be corrected or improved with surgery:

Congenital heart defects – May require open-heart surgery.
Cleft lip and cleft palate – Corrected through reconstructive surgery.
Neural tube defects – Spina bifida may require surgical closure.

Medical Management

Certain conditions require lifelong medical treatment:

Metabolic disorders – Require dietary management (e.g., low-phenylalanine diet for PKU).
Hormonal disorders – Congenital hypothyroidism treated with thyroid hormone replacement.
Neurological disorders – Cerebral palsy may require physical therapy and assistive devices.

Supportive Therapy

Children with birth defects may benefit from:

Physical therapy and occupational therapy.
Speech and developmental therapy.
Assistive devices (e.g., hearing aids, prosthetic limbs).

Prognosis

The long-term outlook for children with birth defects varies widely:

Mild defects may cause no significant health problems.
Severe defects can result in lifelong disabilities or early mortality.
Early diagnosis and intervention can significantly improve quality of life.

Complications

Without proper management and treatment, birth defects can lead to:

Physical disabilities.
Intellectual disabilities.
Increased risk of infections and chronic diseases.
Emotional and psychological impact on families.

Conclusion

Birth defects are a major global health concern, but advancements in medicine, genetic research, and prenatal care have significantly improved outcomes for affected individuals. Early detection, prevention strategies, and appropriate medical intervention are essential in managing and reducing the impact of birth defects.

External Links

This article is a medical stub. You can help WikiMD by expanding it!
Most recent articles Ongoing trials	Wikipedia

@@ Line 1: / Line 1: @@
-[[File:Congenital anomalies world map - DALY - WHO2004.svg|thumb|Congenital anomalies per 100,000&nbsp;inhabitants in 2004.<ref>{{cite web |url=http://www.who.int/healthinfo/global_burden_disease/estimates_country/en/index.html |title=WHO Disease and injury country estimates |year=2009 |work=World Health Organization |accessdate=Nov. 11, 2009}}</ref><div class="references-small" style="-moz-column-count:3; column-count:3;">
+[[File:Congenital anomalies world map - DALY - WHO2004.svg|thumb|Congenital anomalies per 100,000&nbsp;inhabitants in 2004.]]
-{{legend|#b3b3b3|no data}}
-{{legend|#ffff65|less than 160}}
-{{legend|#fff200|160-240}}
-{{legend|#ffdc00|240-320}}
-{{legend|#ffc600|320-400}}
-{{legend|#ffb000|400-480}}
-{{legend|#ff9a00|480-560}}
-{{legend|#ff8400|560-640}}
-{{legend|#ff6e00|640-720}}
-{{legend|#ff5800|720-800}}
-{{legend|#ff4200|800-900}}
-{{legend|#ff2c00|900-950}}
-{{legend|#cb0000|more than 950}}
-</div>]]
 [[File:Rey_Carlos_II.jpg|thumb|[[Charles II of Spain]] was born mentally and physically disabled, probably caused by [[inbreeding]] in the [[House of Habsburg]]]]
+{{Short description|Congenital abnormalities present at birth}}
+'''Birth defects''' are structural or functional abnormalities present at birth that can affect any part of the body, including organs, limbs, metabolism, and development. These defects can vary in severity, ranging from mild conditions that require little to no medical intervention to severe abnormalities that may cause disability or death. Birth defects can be genetic, environmental, or multifactorial in origin.
-'''Birth defects''' (or '''congenital defects''') are defects in a [[baby]] at birth, or which develop in the first month of life.<ref name="isbn0-7216-1489-2">{{cite book |author=Graham, John Whichello 2007 |title=Smith's recognizable patterns of human deformation. |publisher= Saunders |location= 3rd ed, Philadelphia |pages=3 |isbn=0-7216-1489-2 |oclc= |doi= |accessdate=}}</ref>
+== Epidemiology ==
+Birth defects occur worldwide and are one of the leading causes of infant mortality and childhood disabilities. Some key epidemiological facts include:
+* Affect approximately 1 in 33 newborns worldwide.
+* Account for a significant percentage of infant deaths globally.
+* Can be detected prenatally, at birth, or later in life, depending on severity and type.
-There are two main types of congenital defect. The first is caused by [[Genetic disorder|genetic abnormalities]], which are [[hereditary]]. The second is caused by conditions (such as [[infectious disease]]s) which a baby gets from its mother.<ref name=Nelson>{{cite book|title=Nelson's essentials of pediatrics|authors = Kliegman R.M. et al. 2002 |page = 148; 229|publisher = 5th ed, Elsevier Saunders}}</ref>
+== Causes of Birth Defects ==
+Birth defects arise from a combination of genetic, environmental, and unknown factors. The major causes include:
-Sometimes doctors can find out that a baby has a congenital disorder before its birth. They use [[prenatal diagnosis]] and [[screen]]ing tests, such as [[amniocentesis]].<ref name="cdc">Centers for Disease Control and Prevention. [https://www.cdc.gov/ncbddd/bd/research.htm Birth defects research].</ref>
+=== Genetic Factors ===
+Genetic birth defects occur due to mutations in DNA or chromosomal abnormalities. These may be inherited or result from spontaneous mutations.
+* '''[[Chromosomal disorders]]''' – Conditions such as Down syndrome (Trisomy 21), Turner syndrome, and Klinefelter syndrome.
+* '''[[Single-gene mutations]]''' – Conditions such as cystic fibrosis, sickle cell anemia, and Tay-Sachs disease.
-== Genetic defects ==
+=== Environmental Factors ===
-=== Lethal or damaging genes ===
+Certain environmental factors can interfere with fetal development and lead to birth defects:
-Some [[gene]] [[allele]]s (versions of a gene) can damage the baby.
+* [[Teratogens]] – Substances that can cause birth defects, including:
+* '''[[Alcohol]]''' – Causes fetal alcohol spectrum disorders (FASD).
+* '''[[Drugs]]''' – Certain medications, including thalidomide, isotretinoin, and some anticonvulsants.
+* '''[[Infections]]''' – Congenital infections such as rubella, cytomegalovirus (CMV), toxoplasmosis, and syphilis.
+* '''[[Radiation]]''' – Exposure to high levels of radiation can lead to fetal malformations.
+* '''[[Tobacco]] and [[pollutants]]''' – Can increase the risk of low birth weight and congenital abnormalities.
-Conditions like [[dwarfism]] are nearly always [[genetic]] in origin. One type, [[achondroplasia]], happens when a child's [[bone]]s does not grow correctly. Another type is caused by [[pituitary]] malfunction, where the pituitary [[gland]], which puts out growth [[hormone]]s, does not work properly.<ref>[http://www.teachersdomain.org/resource/tdc02.sci.life.gen.lp_disorder/ Inheritance of genetic disorders. ''Teachers' Domain'' 2012]</ref>
+=== Multifactorial Causes ===
+Many birth defects result from a combination of genetic and environmental factors. Conditions such as neural tube defects (spina bifida, anencephaly) and congenital heart defects fall into this category.
-Many [[genetic disorder]]s are caused by [[mutation]]s (or changes) in gene [[allele]]s. Mutations can cause development to go wrong, or a simple [[biochemical]] deficiency (the body does not have enough of an important chemical). In the case of a chemical deficiency, the problem may be curable. For example, [[phenylketonuria]] was a cause of [[mental retardation]]. Doctors came up with a simple test to find which babies have this condition. They found that if these children got treated and followed a strict diet, they could get enough of the chemical they needed. Phenylketonuria now causes few cases of mental retardation.
+== Types of Birth Defects ==
+Birth defects can be categorized based on their impact on different body systems:
-=== Chromosome defects ===
+=== Structural Birth Defects ===
-Another type of genetic defect is caused by errors in [[chromosome]] copying during the [[cell division]] which produces the [[gamete]]s ([[meiosis]]). [[Cell]]s [[cell division|divide]] and copy themselves to produce [[gamete]]s. Sometimes, errors happen in the way that chromosomes are copied during this process. These errors are then copied again and again as cells keep dividing and copying themselves. The most common chromosomal disorder is [[Down syndrome]] ('Mongolism'). This condition happens when a child has three copies of the 21st chromosome, instead of two.
+Structural defects involve physical abnormalities in the body's formation:
+* '''[[Neural tube defects]]''' – Spina bifida, anencephaly, encephalocele.
+* '''[[Congenital heart defects]]''' – Tetralogy of Fallot, atrial septal defect, ventricular septal defect.
+* '''[[Cleft lip and cleft palate]]''' – Affects the mouth and facial structure.
+* '''[[Limb deformities]]''' – Clubfoot, missing or extra fingers (polydactyly, syndactyly).
+* '''[[Gastrointestinal defects]]''' – Hirschsprung's disease, gastroschisis, omphalocele.
-== Maternal [[environment]] ==
+=== Functional or Developmental Birth Defects ===
-=== Infectious diseases ===
+These defects impact organ function, metabolism, or brain development:
-The other main type of congenital disorder is caused by an [[infectious]] disease being passed from mother to child. For example, If a [[pregnant]] woman gets [[rubella]], her child can have many birth defects. Congenital [[syphilis]] was common a century ago, and congenital [[AIDS]] occurs today, and is common in some parts of [[Africa]].
+* '''[[Metabolic disorders]]''' – Phenylketonuria (PKU), galactosemia, maple syrup urine disease.
+* '''[[Neurological disorders]]''' – Cerebral palsy, microcephaly, hydrocephalus.
+* '''[[Sensory impairments]]''' – Congenital hearing loss, blindness.
+* '''[[Endocrine disorders]]''' – Congenital hypothyroidism, adrenal hyperplasia.
-As time passes, screening and [[antibiotics]] has caused the number of [[infection]]s transmitted by the mother to drop. It is a much smaller proportion than a century ago, despite AIDS. Also, maternal [[nutrition]]al defects are much rarer, except in countries where food supply is limited. Therefore, genetic disorders have grown as a proportion of the total congenital defects.
+== Diagnosis ==
+Birth defects can be diagnosed through prenatal screening, newborn screening, and physical examinations.
-=== Substances taken by the mother ===
+=== Prenatal Diagnosis ===
-==== Chemicals ====
+* Ultrasound imaging – Detects physical abnormalities in fetal development.
-Sometimes mothers take chemicals which cause the [[embryo]] damage.<ref>{{cite journal |author=Crider K.S. et al. 2009 |title=Antibacterial medication use during pregnancy and risk of birth defects: National Birth Defects Prevention Study |journal=Arch Pediatr Adolesc Med |volume=163 |issue=11 |pages=978–85 |pmid=19884587 |doi=10.1001/archpediatrics.2009.188 |url=}}</ref> Any substance that causes birth defects is known as a [[teratogen]].
+* Amniocentesis – Used to analyze genetic material for chromosomal disorders.
+* Chorionic villus sampling (CVS) – Early genetic testing for chromosomal abnormalities.
+* Maternal serum screening – Identifies markers for Down syndrome, trisomy 18, and neural tube defects.
-Drugs taken by the mother may affect development of the [[embryo]]. Pregnant women are not allowed to use some drugs. For example, [[thalidomide]] should not be used by a pregnant woman, or it can cause many defects in the [[foetus]].
+=== Newborn Screening ===
+Many countries conduct newborn screening for common metabolic and genetic conditions, such as:
+* Phenylketonuria (PKU)
+* Congenital hypothyroidism
+* Cystic fibrosis
+* Sickle cell disease
-=== Lifestyle ===
+=== Postnatal Diagnosis ===
-If the mother took certain things during pregnancy, these can lead to problems with the baby. Common examples of such things are smoking [[tobacco]], or drinking [[alcohol]]. [[Food]] related: Pregnant women should eat well. If a pregnant woman does not receive enough [[folic acid]] with her food, the child can get [[neural tube]] defects.
+Some birth defects are not detected at birth and only become evident as the child grows. These include developmental delays, sensory impairments, and metabolic disorders.
-==== Sensible precautions ====
+== Prevention ==
-Many women give up [[Smoking|cigarettes]] and [[alcohol]] when [[pregnant]], because this gives the embryo a better chance of developing normally.<ref>{{cite web |url=http://www.consultantlive.com/display/article/10162/1532211 |title=Pre-Prenatal Care: a primary care primer on the future |author= Rutecki, Gregory W. 2010 |publisher=ConsultantLive.com |accessdate=25 September 2010}}</ref>
+While not all birth defects are preventable, several strategies can reduce the risk:
-== How common birth defects are ==
+=== Preconception and Prenatal Care ===
-About 3 percent of all babies have what is called a ''major physical anomaly''. This is something that damages the way the baby looks, or how it functions (its [[physiology]]).<ref>Kumar, Abbas and Fausto (eds) ''Robbins and Cotran's pathologic basis of disease, 7th edition'', p.470.</ref>
+* '''[[Folic acid]] supplementation''' – Reduces the risk of neural tube defects.
+* '''Avoidance of alcohol, smoking, and illicit drugs''' – Prevents fetal alcohol spectrum disorders and other defects.
+* '''Vaccination against infections (e.g., rubella)''' – Prevents congenital infections.
+* '''Managing chronic conditions (e.g., diabetes)''' – Helps control risks associated with pregnancy.
+* '''Avoiding harmful medications during pregnancy''' – Consult with a healthcare provider before taking any drugs.
-Birth defects involving the [[brain]] are the most common problems. They concern about 10 per 1000 live births, compared to [[heart]] problems, at 8 per 1000, [[kidney]] problems at 4 per 1000, and [[limb]]s at 1 per 1000. All other physical anomalies together occur in 6 per 1000 live births.
+=== Genetic Counseling ===
+For individuals with a family history of birth defects, genetic counseling can provide:
+* Risk assessment for inherited conditions.
+* Options for prenatal genetic testing.
+* Reproductive planning strategies.
-Birth defects of the heart have the highest risk of death during childhood. They are the cause of 28% of infant deaths due to birth defects. [[Chromosome|chromosomal]] abnormalities and [[respiration|respiratory]] abnormalities each account for 15%, and brain malformations about 12%. About 10% of deaths in children are because of a [[genetic disease]]. This is more than the number of deaths caused by [[infectious disease]]s.<ref name=Nelson/>
+== Treatment and Management ==
+The management of birth defects depends on their type, severity, and impact on health. Some defects may require surgical correction, while others involve long-term medical care.
-China Birth Deformity Monitoring Centre says that one baby with birth defects is born every 30&nbsp;seconds in China.<ref>{{cite news
+=== Surgical Interventions ===
-| url =| title = Chinese babies born with birth defects every 30 seconds| date = 30 October 2007}}</ref>
+Many structural birth defects can be corrected or improved with surgery:
+* Congenital heart defects – May require open-heart surgery.
+* Cleft lip and cleft palate – Corrected through reconstructive surgery.
+* Neural tube defects – Spina bifida may require surgical closure.
-== Miscarriages ==
+=== Medical Management ===
-Pregnancies which do not come to term ([[miscarriage]]s) have similar causes to birth defects. Many will be due to failures in the genetics controlling development of the [[embryo]].
+Certain conditions require lifelong medical treatment:
+* Metabolic disorders – Require dietary management (e.g., low-phenylalanine diet for PKU).
+* Hormonal disorders – Congenital hypothyroidism treated with thyroid hormone replacement.
+* Neurological disorders – Cerebral palsy may require physical therapy and assistive devices.
-Most clinically apparent miscarriages (two thirds to three-quarters in various studies) occur during the first trimester.<ref name="webmd">{{cite web | last = Rosenthal, M. Sara 1999| title = The second trimester | work = The gynecological sourcebook | publisher = WebMD | url = http://www.webmd.com/content/article/4/1680_51802.htm | accessdate = 18 December 2006 }}</ref><ref name="pmid12336441">{{cite journal |author=Francis O. 1959 |title=An analysis of 1150 cases of abortions from the Government R.S.R.M. Lying-in Hospital, Madras |journal=J Obstet Gynaecol India |volume=10 |issue=1 |pages=62–70 |pmid=12336441 |doi=}}</ref> Chromosomal abnormalities are found in more than half of embryos miscarried in the first 13 weeks.
+=== Supportive Therapy ===
+Children with birth defects may benefit from:
+* Physical therapy and occupational therapy.
+* Speech and developmental therapy.
+* Assistive devices (e.g., hearing aids, prosthetic limbs).
-A pregnancy with a genetic problem has a 95% probability of ending in miscarriage.<ref name="PDR Family Guide 1994">{{cite web |author= |title=Miscarriage: causes of miscarriage |url=http://www.healthsquare.com/fgwh/wh1ch27p3.htm |publisher=[http://www.healthsquare.com/about.htm HealthSquare.com] |accessdate=18 September 2007}}taken word-for-word from pp. 347-9 of: {{cite book |author= |year=1994 |title=The PDR Family Guide to Women's Health and Prescription Drugs |location=Montvale, NJ |publisher=Medical Economics |isbn=1-56363-086-9 |chapter=Chapter 27. What to do when miscarriage strikes |pages=345–50}}</ref> Genetic problems are more likely to occur with older parents; this may account for the higher miscarriage rates observed in older women.<!--
+== Prognosis ==
- --><ref>{{cite web | title = Pregnancy over age 30 | work = MUSC Children's Hospital | url = http://www.musckids.com/health_library/hrpregnant/over30.htm | accessdate = 18 December 2006 |archiveurl = https://web.archive.org/web/20061113233603/http://www.musckids.com/health_library/hrpregnant/over30.htm |archivedate = 13 November 2006}}</ref>
+The long-term outlook for children with birth defects varies widely:
+* Mild defects may cause no significant health problems.
+* Severe defects can result in lifelong disabilities or early mortality.
+* Early diagnosis and intervention can significantly improve quality of life.
-== Related pages ==
+== Complications ==
-* [[List of genetic disorders]]
+Without proper management and treatment, birth defects can lead to:
-* [[Complete Genomics]]
+* Physical disabilities.
+* Intellectual disabilities.
+* Increased risk of infections and chronic diseases.
+* Emotional and psychological impact on families.
-== References ==
+== Conclusion ==
-{{reflist|2}}
+Birth defects are a major global health concern, but advancements in medicine, genetic research, and prenatal care have significantly improved outcomes for affected individuals. Early detection, prevention strategies, and appropriate medical intervention are essential in managing and reducing the impact of birth defects.
-[[Category:Health problems]]
+== See Also ==
-[[Category:Genetic disorders| ]]
+* '''[[Congenital disorder]]'''
-{{stb}}
+* '''[[Genetic counseling]]'''
+* '''[[Neonatology]]'''
+* '''[[Prenatal care]]'''
+== External Links ==
+* [https://www.cdc.gov/ncbddd/birthdefects/index.html CDC – Birth Defects]
+* [https://www.marchofdimes.org/birth-defects March of Dimes – Birth Defects]
+{{Congenital disorders}}
+{{Neonatology}}
+{{stub}}
+{{DEFAULTSORT:Birth Defect}}
+[[Category:Congenital disorders]]
+[[Category:Genetic disorders]]
+[[Category:Pediatrics]]
+[[Category:Public health]]