Birth Defects Metadata: All Measures


Birth defects data are from the Maine CDC's Birth Defects Program. Population data are from the Maine CDC's Office of Data, Research, and Vital Statistics (ODRVS).

Dates Available:


Geographic Resolution:

State, Public Health Districts


In collaboration with the Maine CDC's Maine Birth Defects Program, the Maine EPHT program receives birth defects data annually from the Maine Birth Defects Registry. Birth defects are analyzed, stratified by year, geographic resolution, sex, and mother’s age, when appropriate.

The dataset contains rates and numbers for the following birth defects:

     1. Anencephaly
     2. Cleft lip with cleft palate
     3. Cleft lip without cleft palate
     4. Cleft palate without cleft lip
     5. Down syndrome
     6. Gastroschisis
     7. Hypoplastic left heart syndrome
     8. Hypospadias
     9. Limb deficiencies
    10. Spina bifida
    11. Tetralogy of Fallot
    12. Transposition of the great arteries (vessels)


This data set supports efforts to improve public health in Maine and contributes to the U.S. CDC’s National Environmental Public Health Tracking (EPHT) Network. A key activity of participants in this network is to track and make available environmental health measures on state and national data portals. Measures derived from the data set described here can be used to compare birth defect rates across the state, between groups of people, and over time.

The Maine Tracking Network, a member of the National EPHT Network, connects communities, public health professionals, policy makers, state agencies, and others to the data they need to monitor public health, respond to health concerns, prioritize resources for public health action, and evaluate prevention activities. Maine tracks certain health effects, exposures, and environmental hazards that have known relationships, as well as some health effects and environmental hazards that have suspected relationships. By making health and environmental data available through the Maine Tracking Network, more people have access to data they need to think critically and hypothesize about health outcomes and their relationships to conditions in the environment.

Supplemental Information:

Birth defects are reported to the Maine Birth Defects Program and entered into the Maine Birth Defects Registry (MBDR) database. The MBDR uses passive case finding with active case follow-up to verify, define and classify birth defects.  Birth cases are coded and classified using the ICD9-CM or ICD10-CM coding system. The Maine EPHT program receives calendar year birth defect data based on date of birth, date of death, or prenatal diagnosis date (if birth and death dates are not available). Birth defect data on the Maine Tracking portal include total counts of birth defects ascertained and reported within the first year of birth, fetal death, or spontaneous abortion. Some data may have been suppressed, in accordance with Maine CDC privacy policies.

The included birth defects are described as follows:

Birth defect



Partial or complete absence of the brain and skull.

Cleft lip with cleft palate

A defect in the upper lip resulting from incomplete fusion of the parts of the lip, with an opening in the roof of the mouth.

Cleft lip without cleft palate

A defect in the upper lip resulting from incomplete fusion of the parts of the lip.

Cleft palate without cleft lip

An opening in the roof of the mouth resulting from incomplete fusion of the shelves of the palate. The opening may involve the hard palate only, the soft palate only, or both.

Down syndrome (Trisomy 21)

The presence of three copies of all or a large part of chromosome 21.


A congenital opening or fissure in the anterior abdominal wall lateral to the umbilicus through which the small intestine, part of the large intestine, and occasionally the liver and spleen, may herniate. 

Hypoplastic left heart syndrome

A condition in which the structures on the left side of the heart and the aorta are extremely small, insufficient to support systemic circulation and with normally related great arteries.


Displacement of the opening of the urethra (urethral meatus) ventrally and proximally (underneath and closer to the body) in relation to the tip of the glans of the penis.

Limb deficiencies

Complete or partial absence of the upper arm (humerus), lower arm (radius and/or ulna), wrist (carpals), hand (metacarpals), fingers (phalanges), thigh (femur), lower leg (tibia and/or fibula), ankle (tarsals), foot (metatarsals), or toes (phalanges).

Spina bifida

Incomplete closure of the vertebral spine (usually posteriorly) through which spinal cord tissue and/or the membranes covering the spine (meninges) herniate.

Tetralogy of Fallot

The simultaneous presence of a ventricular septal defect (VSD), pulmonic and subpulmonic stenosis, a malpositioned aorta that overrides the ventricular septum, and right ventricular hypertrophy.

Transposition of the great arteries (vessels)

Transposition of the aorta and the pulmonary artery such that the aorta arises from the right ventricle (instead of the left) and the pulmonary artery arises from the left ventricle (instead of the right).

For additional information and coding definitions, see the Birth Defects Descriptions from the National Birth Defects Prevention Network.

Analyses are based on the place of residence at the time of birth. Additional, topic-specific considerations include the following.

  • Hypospadias and Limb deficiencies: surveillance in Maine began in 2008. Thus, data for these two measures are available starting in 2009.

Entity and Attribute Overview:

The dataset includes: year, geographic resolution, measure, and sex and mother’s age when appropriate.

Data Limitations:

Comparisons of birth defects data across states are limited by differences in surveillance systems. Not all states in the U.S. conduct birth defects surveillance. Among those states that do, there is significant variability between surveillance systems. These differences include:

  • Ascertainment methods (active, passive, passive with follow-up).
  • Data source, coding, availability of verbatim description, and case verification.
  • Some surveillance systems include spontaneous fetal deaths and/or prenatally diagnosed cases and elective terminations, while others may only include birth defects among live births.
  • Variability in the cutoff for gestational age in fetal deaths.
  • Differences in case definitions.
  • Classification may differ across states' surveillance systems. Classification as isolated, multiple, or syndromic poses challenges for coding birth defects and ensuring cases are not over-represented. 

Address data is based on address at delivery, not conception (the more relevant period for birth defects-related exposures), which limits the ability to associate environmental exposures with birth defect prevalence.

When prevalence is based on small numbers, the rate is considered unstable. In Maine, the number of births, fetal deaths, and spontaneous abortions and resulting birth defects are small. This means that one or more instances of a birth defect can dramatically change the prevalence, making it hard to tell random differences in the numbers from meaningful differences in the risk of birth defects.

The number of birth defects with mandated reporting has changed over time. Mandated reporting for 9 of the 12 birth defects to the Maine Birth Defects Registry began in May 2003. Beginning in May 2008, two more birth defects were added to the mandated reporting list (hypospadias and limb reduction deformities).

Access Constraints:

Publicly available data are suppressed in accordance with the privacy policies of the Maine CDC and the Maine Birth Defects Registry, in order to protect confidentiality.

More Information:

Suggested Citation for Data Displays:

Maine Center for Disease Control and Prevention, Maine Tracking Network. Birth Defects Metadata: All Measures. Available online: Accessed on [date accessed].