Frequently Asked Questions - Birth Defects
What is birth defects tracking?
Birth defects tracking, or surveillance, is the ongoing collection, analysis, and interpretation of birth defects data in a population of children from birth up to age one. Massachusetts law requires the reporting of birth defects to the Massachusetts Department of Public Health (MDPH). The Massachusetts Center for Birth Defects Research and Prevention was established in 1996 within MDPH as an active state-wide, population-based birth defects registry. The EPHT portal allows users to review both birth defects data and environmental data to help determine the need for follow-up investigations.
Why is the EPHT Program tracking birth defects?
In 2002, Massachusetts was one of seven states across the U.S. to be awarded funds from the U.S. Centers for Disease Control and Prevention (CDC) to track health conditions thought to be impacted by the environment. By sharing data about the occurrence of birth defects in Massachusetts, the EPHT Program hopes to better understand the potential for environmental factors to play a role.
How is information collected on birth defects in Massachusetts?
The Massachusetts Birth Defects Monitoring Program (MBDMP) is an active, statewide surveillance program. It is part of the Massachusetts Center for Birth Defects Research and Prevention within the Massachusetts Department of Public Health/Bureau of Family Health and Nutrition. Birthing hospitals and other pediatric care centers across the state regularly submit birth defect diagnoses to the Center. These diagnoses are verified through medical record abstraction conducted by Center staff; during the abstracting process additional important demographic information is collected. Also, vital records, including birth certificates, fetal death reports, and infant death certificates are reviewed for qualifying diagnoses. The diagnoses are reviewed by a clinical geneticist and entered into a secure confidential electronic database maintained by the MBDMP.
If my child was born with a birth defect, will information on my child or family be available to the public?
No. Only summary statistics on the occurrence of birth defects in Massachusetts will be available through the EPHT network. No personally-identifying information on your child or your family will ever be disclosed. Extensive procedures are in place to guarantee the confidentiality of the birth defects data and to protect the privacy of families. These procedures uphold MDPH ethical and legal obligations to safeguard confidentiality and they fully comply with the strict requirements of state and federal laws.
What types of birth defects are included on the EPHT network?
Twelve birth defects are included on the EPHT network. They include: anencephaly, spina bifida (without anencephaly), hypoplastic left heart syndrome, tetralogy of Fallot, transposition of the great arteries (vessels), cleft lip with or without cleft palate, cleft palate without cleft lip, hypospadias, gastroschisis, upper limb deficiencies, lower limb deficiencies, and trisomy 21. Definitions of these birth defects can be found in the glossary.
What statistic is used to measure the number of birth defects in a county or the state of Massachusetts as a whole?
The occurrence of birth defects in an area is estimated by calculating a statistic called prevalence. Prevalence is defined generally as the number of individuals with a disease or condition over a specified period of time divided by the number of individuals at risk during the same period. For birth defects, prevalence is defined as the number of infants less than one year of age with a birth defect divided by the number of live births over a specified period of time, typically over a one-year period.
Prevalence is usually expressed as the number of birth defect births per 10,000 live births. It is calculated using the formula:
|number of infants with birth defect(s)|
total number of live births
The number of live births in the denominator of the prevalence estimate is an approximation of the number of total pregnancies during the time period of interest. Because the number of pregnancies cannot be determined, the number of total births is used as an approximation.
How are prevalence estimates interpreted?
To best interpret the prevalence estimate for a county or the state a statistic referred to as a confidence interval (CI) is used. Confidence intervals are commonly used to assess the magnitude and stability of disease rates or, in this case, the prevalence of birth defects. The CI can also help determine if the prevalence estimate for a county is statistically significantly different from the statewide experience for that birth defect. That is, does the difference between the two prevalence estimates most likely represent normal random variation in prevalence estimates or is it a statistically significant difference?
The CI represents a range of values that has a 95% probability of including the true prevalence. The width of the confidence interval reflects the size of the population and the number of birth defects. The prevalence estimate for a smaller population with fewer birth defects, such as that of a more sparsely populated county in the state, will lead to a wider confidence interval. In contrast, the confidence interval for the prevalence of a birth defect for the state as a whole will be narrower.
As mentioned, one method for determining if a given prevalence estimate is statistically significantly different from another is to compare their confidence intervals. The prevalence of birth defects in a county can be compared to the prevalence of birth defects in the state as a whole using the two CIs. If the CI for one county does not overlap the CI of the state, then it can be concluded that the prevalence estimates are statistically significantly different from each other. If they do overlap, then it can be concluded that the birth defect prevalence estimates are not likely to be statistically significantly different.
What is the relationship between birth defects and the environment?
Some research on environmental hazards and associations with birth defects is available; however, much more work is needed to more fully understand the relationship between the environment and birth defects.
Environmental substances that can cause birth defects are called teratogens. These include alcohol, certain drugs/medications, infections and certain chemicals.
Some endocrine-disrupting chemicals, including polychlorinated biphenyls (PCBs), dioxins, and pesticides, have been linked to nervous system defects and developmental problems such as reduced muscle tone and response.
The CDC has reported that living near a hazardous waste site has been identified as a possible risk factor for birth defects such as neural tube defects. Neural tube defects are defects in the development of the brain and spinal cord. Exposure to disinfection by-products in drinking water such as trihalomethanes, or THM, may increase the risk of some types of birth defects.
Most experts believe that the majority of birth defects are likely to be the result of a complex interaction between genetic predisposition and environmental factors.
Are there other known risk factors for birth defects?
Some birth defects are caused by genetic problems. Sometimes, these birth defects run in families, but other times they will occur even when there is no one else in the family who has this problem.
If a woman takes certain drugs during her pregnancy, the chance of birth defects in her offspring is increased. Also, women who smoke and use alcohol while pregnant have a higher risk of having a baby with certain birth defects.
Folic acid (vitamin B9) deficiency is related to certain birth defects. Studies have shown that the presence of adequate amounts of folic acid in the mother’s system during the period around conception may help prevent defects of the brain and spinal cord.
Women over the age of 35 years have a higher chance of having a child with Down syndrome than women who are younger. Teenage mothers are more likely to have a baby born with gastroschisis —a defect in the abdominal wall.
It is important to note, however, that the Massachusetts Center for Birth Defects Research and Prevention estimates that approximately 80% of birth defects in the state have unknown causes.
What are the limitations of the data?
- Defects related to early fetal deaths and/or terminations are not included in prevalence estimates. Furthermore, defects that are not diagnosed at birth, do not need hospitalization, or are diagnosed after age one may be underreported.
- There is the possibility of misclassification due to a vague or miscoded diagnosis which may affect birth defect prevalence measures. Quality control measures such as careful medical record abstraction minimize this error.
- It is important to note that prevalence estimates are based on the residential location of the mother at the time of the child’s diagnosis.
- Counts and prevalence estimates may differ slightly from those contained in other publications. These differences may be due to file updates, differences in calculation methods (such as grouping ages differently or rounding off numbers at different points in calculations), updates or differences in population estimates, and differences in birth defects definitions.
- Only diagnoses confirmed before one year of age are included.
What are the Codes and Exclusions for each birth defect category?
ICD-9 / BPA1
|Cleft lip w/ and w/o cleft palate||749.101-749.290||Excludes isolated alveolar ridge, cleft gum.|
|Cleft palate w/o cleft lip||749.001-749.090||Excludes isolated submucous cleft, bifid uvula.|
|Hypospadias, 2nd or 3rd degree||752.606-752.627||Excludes 1st degree hypospadias and NOS hypospadias|
|Hypoplastic left heart syndrome||746.700||
|Limb deficiency, lower limbs||755.300-755.390||
|Limb deficiency, upper limbs||755.200-755.290||
|Spina bifida||741.001-741.999||Includes cases with and without associated hydrocephaly.|
|Tetralogy of Fallot w/ and w/o pulmonary atresia||745.185, 745.200, 747.310||
|Transposition of the great arteries||745.100, 745.110, 745.186, 745.190||d-Transposition of the great arteries; excludes corrected (L-transposition) of the great arteries|
|Trisomy 21 (Down syndrome)||758.000-758.090||
|1 Coding scheme derives from International Classification of Diseases (ICD) 9th Revision/British Pediatric Association (BPA), 1979.|