To collect data on birth defects, trained MACDP records abstractors visit birth and pediatric hospitals and genetic laboratories to review in-patient medical records of infants and fetuses of [greater than or equal to] 20 weeks' gestation.
For MACDP purposes, prevalence is defined as the number of infants and fetuses with a major birth defect that were delivered during a specified period divided by the number of live births during that period.
The lower prevalence of defects among black and Hispanic infants might reflect an actual lower prevalence among these groups; however, racial and ethnic variation in health-insurance coverage, diagnosis of nonsymptomatic defects through pediatric and subspecialty care, and ascertainment of these defects by MACDP's hospital-based methods also might affect differences in defect prevalence.
Second, the specific defect inclusion and exclusion criteria used by MACDP might differ from those used by other surveillance programs, resulting in differences in prevalence estimates (10).
During 1981-1989, MACDP and MADDSP combined identified 92 children with possible FAS: MACDP uniquely identified 50 (54%) of these possible cases; MADDSP uniquely identified 31 (34%); and both registries identified 11 (12%).
Third, the prevalence derived using the capture-recapture method probably is an underestimate because of some "positive dependence" between the two surveillance systems (7) (i.e., children identified by MACDP may have had an increased likelihood of being identified by MADDSP because a child already identified as having FAS probably is more likely to have cognitive evaluations and to enter special education).
To determine whether personnel completing birth certificates could have used medical record review to determine an infant's FAS status, the date of diagnosis reported in the MACDP file was compared with the date of birth.
From 1989 through 1992, MACDP identified 35 FAS cases (overall rate: 2.3 per 10,000 births).
Diagnostic information for this report is grouped into 44 categories on the basis of a classification system developed at the MACDP. The categories represent a variety of anatomic abnormalities and reflect the malformations most frequently addressed in scientific literature.
The ratio of the prevalence for the MACDP compared to the CBDMP in each defect category was also estimated.
Only one of the 44 diagnostic categories, microcephalus, met these criteria for both races simultaneously; the prevalence for microcephalus was higher in the CBDMP than in the MACDP. The prevalence for stenosis/atresia of the duodenum among blacks and for scoliosis/lordosis among whites was higher in the CBDMP when compared with the MACDP.
The MACDP has a higher prevalence of spina bifida, aortic stenosis, encephalocele, and trisomy 21 (Down's Syndrome).