What is a birth defect?
A birth defect is an abnormality in the structure or function of an organ that develops in a baby before birth. Birth defects can affect almost any part of the body. They are also called congenital anomalies. Usually, the abnormality involves a body part that is missing or malformed. Other times, it may involve problems with metabolism, or how an organ works. Babies born with birth defects often need special care to thrive.
Although birth defects are rare compared to other adverse birth outcomes like low birth weight or prematurity, they are the leading cause of death in the first year of life.
What are known risk factors for birth defects?
The cause of about 70% of birth defects in the state is unknown. Most are likely due to a mix of genetic, behavioral, and environmental factors.
Some known risk factors include:
- Having someone in your family with a birth defect. Sometimes birth defects are caused by inherited genetic mutations passed down from a parent to a child
- Using tobacco, drinking alcohol, and/or taking certain drugs or medications during pregnancy
- Not getting enough folic acid (vitamin B9) each day during the time around conception through the first several months of pregnancy. This can increase the risk of neural tube defects, which affect the brain and/or spinal cord
- Age. Having a child after age 35 increases the risk of Down syndrome. Having a child as a teenager increases the risk of gastroschisis – a defect in the abdominal wall.
- Certain infections during pregnancy, such as rubella (also called German measles) or Zika
- Having certain medical conditions, such as uncontrolled diabetes
Although not all birth defects can be prevented, take steps before pregnancy to increase the chance of having a baby with the best health possible.
What is the relationship between birth defects and the environment?
It is not clear how many birth defects are related to environmental exposures. Researchers are looking at a wide variety of possibilities and more work is needed.
Current research indicates:
- Living near a hazardous waste site is a possible risk factor for birth defects
- Exposure during pregnancy to disinfection byproducts in drinking water, such as trihalomethanes (THM), may increase the risk of some birth defects
- Exposure to ionizing radiation during pregnancy can cause birth defects. For this reason, medical providers ask about pregnancy before giving x-rays to prevent risk to the developing baby.
How does MA EPHT track birth defects?
MA EPHT collaborates with the Massachusetts Birth Defects Monitoring Program (MBDMP) to present data on the occurrence of birth defects in tables, graphs, and maps.
MBDMP tracks:
- What type of birth defects are occurring
- How often they are occurring
- Where they are occurring
Massachusetts law requires hospitals and other medical facilities to report structural birth defects to DPH when diagnosed before age 1.
MA EPHT provides data for the following 12 birth defects: anencephaly, spina bifida (without anencephaly), hypoplastic left heart syndrome, tetralogy of Fallot, transposition of the great arteries (vessels), cleft lip with cleft palate, cleft lip without cleft palate, cleft palate without cleft lip, hypospadias, gastroschisis, limb deficiencies, and trisomy 21.
Why does MA EPHT track birth defects?
Tracking helps us understand the connection between birth defects and the environment. MA EPHT studies the trends and patterns in these data across time, geography, and demographics. This helps us better understand how the environment influences our health. It also allows us to identify populations at risk for, or suffering from, poor health outcomes. This information is used to inform public health policy and prevention efforts.
Available data
Use the Explore birth defects data link on this page to access the following measures for birth defects:
- Annual statewide prevalence per 10,000 live births
- Prevalence per 10,000 live births during a 5-year period by county and statewide
The most current available data will be shown. Be sure to check the site periodically as new data is added. To protect privacy, no information is shown that could potentially identify an individual.
Data considerations
- Birth defects prevalence is the number of infants (babies younger than one year old) with a birth defect divided by the number of live births over a period (typically one year). It is usually expressed as the number of birth defects per 10,000 live births.
- Estimates are based on the residential location of the birthing parent at the time of the child’s diagnosis
- MBDMP has been collecting information on live births and stillbirths with birth defects born to Massachusetts residents since 1997. Beginning in 2012, MBDMP started to collect data on birth defects among pregnancies that ended in other types of losses, including terminations at any gestational age and miscarriages less than 20 weeks gestation.
- Diagnoses made after age one are not included in this dataset
Birth defect descriptions
Anencephaly
Anencephaly is a birth defect that affects the closing of the neural tube during pregnancy. The neural tube is a narrow channel that folds and closes during the third and fourth weeks of pregnancy to form the brain and spinal cord. Anencephaly occurs when the part of the neural tube that forms the brain does not close. This results in the baby lacking parts of the brain, skull, and scalp.
Cleft lip
A cleft lip is a congenital defect of the upper lip in which there is incomplete closure. The opening in the lip can be a small slit in the lip or a large opening that goes through the lip into the nose.
Cleft palate
A cleft palate is an opening in the roof of the mouth, called the palate. A cleft palate can occur when the two sides of the palate do not come together correctly.
Gastroschisis
A birth defect in which a portion of an infant’s intestines stick out of the body through a small hole in the body wall beside the umbilical cord. The body wall defect can be small or large and other organs such as the liver can be involved.
Hypoplastic left heart syndrome(HLHS)
A type of congenital heart defect that affects normal blood flow through the heart. Several parts of the left side of the heart do not fully develop.
Hypospadias
A birth defect among boys in which the opening of the urethra is located somewhere along the underside of the penis instead of at the tip. The urethra is the tube that carries urine from the bladder to the outside of the body. This defect occurs when the urethra does not complete its development during the pregnancy.
Limb deficiency, upper arms / lower legs
Upper limb deficiency defects occur when a part of or the entire arm (upper limb) of a fetus fails to form completely during pregnancy. Lower limb deficiency defects occur when a part of or the entire leg (lower limb) of a fetus fails to form completely during pregnancy.
Spina bifida (without anencephaly)
The neural tube is a narrow channel that folds and closes during the third and fourth weeks of pregnancy to form the brain and spinal cord. Spina bifida is a neural tube defect that happens if part of the neural tube does not close all the way.
Tetralogy of fallot (TOF)
A type of congenital heart defect that changes the normal flow of blood through the heart. Tetralogy of Fallot is a combination of four defects: (1) a hole in the wall between the ventricles (two lower chambers of the heart), called a ventricular septal defect; (2) narrowing of the tube that carries blood from the heart to the lungs, called pulmonary stenosis; (3) the aorta (the tube that carries oxygen-rich blood to the body) grows from both ventricles, rather than from the left ventricle only; and (4) a thickened muscular wall of the right ventricle, called right ventricular hypertrophy.
Transposition of the great arteries (vessels)
A type of congenital heart defect that occurs when the two main arteries going out of the heart—the pulmonary artery and the aorta—are switched in position, or “transposed.”
Trisomy 21 (Down syndrome)
Down syndrome is a condition in which a baby is born with an extra chromosome, chromosome 21. This extra copy changes the normal development of the body and brain and can cause developmental and physical problems for the baby.
Source: U.S. Centers for Disease Control and Prevention (CDC), Specific Birth Defects and Other Health Conditions, November 2024
Related links
Additional resources
Massachusetts
- Boston University Slone Epidemiology Center: The Slone Epidemiology Center is collaborating with the Massachusetts Center for Birth Defects Research and Prevention to conduct surveillance and research aimed at the prevention of birth defects. The Center’s work includes two national case-control studies to identify risk factors for birth defects.
National
- U.S. Centers for Disease Control and Prevention (CDC) birth defects: Birth defects information and resources
- CDC National Environmental Public Health Tracking for birth defects : CDC’s National Environmental Public Health Tracking website
- National Birth Defects Prevention Network: National standards for birth defects surveillance, reports, and other information
- National Birth Defects Prevention Study: A collaboration between CDC and programs across the U.S. to find the causes of birth defects
- National Institute of Child Health and Human Development (NICHD) congenital anomalies: NCIHD conducts and supports a range of research on congenital anomalies
- March of Dimes: Non-profit organization providing information on pregnancy, prematurity, birth defects, and more
- International Clearinghouse for Birth Defects Surveillance and Research: Non-profit organization affiliated with the World Health Organization (WHO) to conduct worldwide surveillance and research into the occurrence and possible causes of birth defects