ConditionChildren's health
Congenital Anomalies (Birth Defects)
Congenital anomalies, also called birth defects, are differences in how a baby's body forms or works that are present at birth. They affect about 1 in 33 babies in the US. Common examples are heart defects, cleft lip and palate, neural tube defects such as spina bifida, clubfoot and Down syndrome. Causes include genetic changes, infections, medicines, alcohol and other exposures in pregnancy, though often no cause is found. Many are treatable, and some can be prevented.
Also called: Birth defects, congenital disorders, congenital malformations, congenital abnormalities
At a glance
- What they are
- Structural or functional differences present at birth.
- How common
- About 1 in 33 US births (3%).
- Most common
- Heart defects, cleft lip and palate, Down syndrome, neural tube defects, clubfoot and hypospadias.
- Causes
- Genetic and chromosomal changes, infections, alcohol, some medicines, maternal diabetes and obesity. Often unknown.
- Detection
- Prenatal screening and ultrasound, newborn examination and newborn screening.
- Prevention
- Folic acid before and during pregnancy, avoiding alcohol and smoking, vaccinations, and managing health conditions.
When to get help
Call 911 or go to the ER
- A newborn with blue or gray skin, fast or labored breathing, or poor feeding with sweating (possible serious heart defect)
- A newborn with green vomiting, a swollen belly, or no stool in the first 48 hours
- An open defect on the back or abdomen, or a baby who is floppy or hard to wake
See a doctor within a day or two
- A baby who is not feeding well or not gaining weight
- Milk coming out of the nose during feeds
- No wet diaper in 24 hours after the first few days of life
Book a routine appointment
- Concerns about the shape of the head, face, limbs, hips or feet
- Delays in reaching developmental milestones
- Planning a pregnancy with a family history of birth defects, diabetes, epilepsy or other conditions needing medicines
What congenital anomalies are
Most body structures form in the first 3 months of pregnancy, often before a woman knows she is pregnant. Anomalies can affect:
- Structure: how a body part is shaped, such as a heart defect or cleft lip
- Function: how a body system works, such as hearing loss, metabolic disorders or blood disorders
They range from minor (an extra finger) to serious and life-threatening (complex heart defects). Birth defects are a leading cause of infant deaths in the US.
Common types
| Category | Examples |
|---|---|
| Heart | Congenital heart defects: the most common birth defect, about 1 in 100 babies |
| Face and mouth | Cleft lip and palate |
| Brain and spine | Neural tube defects such as spina bifida and anencephaly, hydrocephalus |
| Chromosomal | Down syndrome (trisomy 21), trisomy 18, trisomy 13, Turner syndrome |
| Limbs and bones | Clubfoot, hip dysplasia, limb reduction defects |
| Genital and urinary | Hypospadias, undescended testicles, kidney malformations |
| Gut | Gastroschisis, diaphragmatic hernia, esophageal atresia, anorectal malformations |
| Eye and ear | Congenital cataracts, hearing loss |
Causes and risk factors
For many birth defects, the cause is unknown or a combination of genetic and environmental factors.
Genetic
- Chromosomal changes: extra, missing or rearranged chromosomes, as in Down syndrome or 22q11.2 deletion syndrome
- Single gene changes inherited from parents or arising new
- Family history of a birth defect
Exposures in pregnancy
- Alcohol: causes fetal alcohol syndrome. No amount is known to be safe
- Smoking: linked with cleft lip and palate and other defects
- Certain medicines: including isotretinoin, valproate, some other epilepsy drugs, warfarin, and ACE inhibitors later in pregnancy
- Infections: rubella, cytomegalovirus, toxoplasmosis, syphilis and Zika virus. See TORCH infections
- Recreational drugs and some chemicals
Maternal health
- Poorly controlled diabetes before and in early pregnancy
- Obesity
- Low folate levels
- Phenylketonuria not controlled with diet
- Older maternal age, which increases the risk of chromosomal conditions
How birth defects are found
During pregnancy
- Screening blood tests and cell-free DNA tests estimate the chance of chromosomal conditions
- Ultrasound: the detailed anatomy scan at about 18 to 22 weeks detects many structural defects
- Fetal echocardiography for suspected heart defects
- Diagnostic tests: chorionic villus sampling or amniocentesis confirm chromosomal and genetic conditions
Finding a defect before birth allows planning for delivery at a hospital with the right specialists.
After birth
- Newborn physical exam
- Pulse oximetry screening for critical heart defects
- Newborn blood spot screening for metabolic, hormone and blood conditions
- Newborn hearing screening
- Later checkups may find defects that only become clear as the child grows
Treatment
Treatment depends on the condition and may include:
- Surgery: for heart defects, cleft lip and palate, spina bifida, clubfoot casting and surgery, and gut defects. Some surgery can even be done before birth
- Medicines: for heart, hormone or metabolic conditions
- Special diets: for metabolic disorders
- Therapies: physical, occupational, speech and feeding therapy
- Assistive devices: hearing aids, braces and mobility aids
- Early intervention and educational support
Many children with birth defects are cared for by a team of specialists and grow up to lead healthy lives.
Prevention
Not all birth defects can be prevented, but the risk can be reduced:
- Take 400 micrograms of folic acid daily starting at least 1 month before conception and through early pregnancy. This greatly reduces the risk of neural tube defects. Women at higher risk may be advised a higher dose by their doctor
- Avoid alcohol, smoking and recreational drugs during pregnancy and when trying to conceive
- Review medicines with a doctor before pregnancy. Do not stop prescribed medicines without advice
- Control diabetes and reach a healthy weight before pregnancy
- Get vaccinated against rubella and other infections before pregnancy
- Prevent infections: wash hands, avoid undercooked meat and cat litter, and protect against Zika in affected areas
- Attend prenatal care early
Frequently asked questions
What are congenital anomalies?
Congenital anomalies, or birth defects, are differences in the structure or function of a baby's body that are present at birth. They range from minor to serious and include heart defects, cleft lip and palate, spina bifida and Down syndrome.
What are the most common birth defects?
In the US, the most common are congenital heart defects, followed by cleft lip and palate, Down syndrome, clubfoot, hypospadias and neural tube defects such as spina bifida.
What causes birth defects?
Causes include genetic and chromosomal changes, infections during pregnancy, alcohol, smoking, certain medicines, poorly controlled diabetes and obesity. In many cases, no single cause is found and it is likely a combination of genetic and environmental factors.
Can birth defects be prevented?
Some can. Taking folic acid before and during early pregnancy, avoiding alcohol and smoking, controlling diabetes, reviewing medicines, getting vaccinated and preventing infections all reduce the risk. Many birth defects, however, cannot be prevented.
Can birth defects be detected before birth?
Many can. Prenatal blood tests, cell-free DNA screening, and the mid-pregnancy anatomy ultrasound detect many chromosomal and structural conditions. Diagnostic tests such as amniocentesis can confirm genetic conditions. Some defects are only found after birth.
Sources
This guide was written from current patient and clinical guidance, including:
- CDC: Birth Defects, data and statistics; Facts about birth defects
- World Health Organization: Congenital disorders fact sheet
- ACOG: Screening for Birth Defects (FAQ)
- March of Dimes: Birth defects and other health conditions
- US Preventive Services Task Force: Folic Acid Supplementation to Prevent Neural Tube Defects
- NIH Eunice Kennedy Shriver NICHD: Birth defects