Birth Defects Clusters
What is a birth defect?
What is a birth defect cluster?
What causes clusters?
Why investigate birth defects clusters?
What characterizes a cluster?
Who should I report a cluster to?
What information should be in a cluster report?
What about the confidentiality?
What will happen after I make a report?
- A birth defect is an abnormality that is present at birth, such as a missing limb, malformed heart, or Down syndrome.
- Birth defects occur in about 3% of births--more than 122,000 babies in the US every year. Women of all ages, races/ethnicities, education, and income levels are at risk for having a baby with a birth defect.
- The causes of most birth defects are unknown. However, through research and surveillance we may identify causes and develop prevention measures.
- When too many babies are born with the same birth defect for a defined period and geographical area, this is called a cluster.
- Birth defects, like all other health conditions, often occur in clusters.
- Most happen by coincidence or chance alone.
- Others can be explained by changes in diagnostic practices or hospital referral patterns.
- Rarely, a cluster is due to an environmental exposure that all the mothers or fathers have in common.
- The purpose of evaluating cluster reports is to determine if an increase in birth defects has occurred and, if so, whether there is an exposure that may be linked.
- A cluster investigation cannot answer parents' questions about why their child was born with a birth defect. Causes can only be identified through large case-control interview studies, like the National Birth Defects Prevention Study.
- A large increase in babies born with the same birth defect and
- A prenatal exposure that the mothers or fathers have in common, such as illness, diet, medication, alcohol or drugs, or chemicals at home or work.
- Suspected clusters should be reported to the public health officer in your county health department or the state department of health.
To evaluate the report, investigators need to know:
- For each child, the names of the mother and baby, date and hospital of birth, and all the child's diagnoses,
- Ideas about environmental exposures during early pregnancy. To determine if the cases may have the same cause, investigators need to know what exposures all the mothers have in common.
- State law requires that all identifying information be kept confidential.
- Only investigating staff have access to this information
- Public reports are limited to summary data.
Investigators will determine:
- If all the babies have the same birth defect
- Whether there are more babies with the same birth defect than would normally be expected in a certain area for a certain time period (many conditions are more common than people realize).
- If there is a common exposure that may explain the increase.
- Parents may be asked to provide more information and to give permission for investigators to review their medical records.
- A written report will be made of the investigation's findings.
Adapted with permission from the National Birth Defects Prevention Network.
For More Information:
Birth Defects Epidemiology & Surveillance
Texas Department of State Health Services
1100 W. 49th Street
Austin, TX 78756
Email: Cluster Investigations