The registry—a system for recording and tracking malformations in the population—is the backbone of birth defects epidemiology. The California Birth Defects Registry is a database of diagnostic and demographic information drawn from over 3.9 million births. Our data collection and reporting procedures—reflecting 20+ years experience—ensure that data is accurate, comprehensive, consistent and useful. WHO’S IN THE REGISTRY?
We gather information on children with specified birth defects— major malformations with significant medical and public health impact. We look at live births, medically indicated pregnancy terminations, and stillbirths occurring after 20 weeks gestation.
Our registry covers a representative subset of California counties—Fresno, Kern, Kings, Madera, Merced, Orange, Riverside, San Bernardino, San Diego, San Joaquin, Stanislaus and Tulare—comprising 44% of the state’s births and reflecting its racial/ethnic diversity. (Limited data collection occurs in additional counties for research purposes.) COLLECTING MEDICAL INFORMATION We use broad casefinding criteria following well-documented procedures to ensure complete ascertainment. Program staff review logbooks and other records at hospitals where births occur or where children are treated, as well as genetic clinics and chromosome laboratories. Data collection specialists review the entire medical chart for each potential case identified, recording any diagnoses made prenatally, after birth and up to 1 year. Only conditions confirmed by physicians using appropriate tests (for example, x-rays, cardiac catheterization, surgery, autopsy) are included. Since 1998, medical geneticists—specialists in birth defects—have evaluated case records to ensure diagnostic criteria are met. LINKING WITH VITAL STATISTICS RECORDS Information is coded and entered into the database. We merge multiple records on the same child, who may have been treated at several facilities or had many hospital admissions. Case files are linked to Vital Statistics records (birth or fetal death certificates) which supply demographics, including parents’ races, ages, and residence. ANALYZING AND REPORTING RESULTS
To minimize the random variation inherent in small numbers, we report:
|5 year averages|
|Estimated figures for counties derived from registry rates and local population size.|
To protect confidentiality, we do not report:
|Rates based on fewer than 5 cases|
|Potentially identifying information.|
SAFEGUARDING CONFIDENTIALITY We have a moral and legal obligation to protect and keep confidential all information that could potentially identify children or their families.
Confidentiality Requirements and Procedures