POPULATION STUDY OF CONGENITAL HYPOTHYROIDISM AND ASSOCIATED BIRTH-DEFECTS, ATLANTA, 1979-1992

Very little data are available from population-based studies on congen ital hypothyroidism (CH) epidemiology and patterns of associated birth defects. By linking data from two population-based registries, we des cribe the epidemiology of CH and associated defects in Atlanta from 19 79-1992, Cases included all infants with CH born from 1979-1992 to mot hers residing in the metropolitan Atlanta area at the time of birth. W e ascertained CH cases by reviewing newborn screening records and reco rds of the Metropolitan Atlanta Congenital Defects Program (MACDP), a population-based registry of all serious birth defects diagnosed durin g a child's first year of life. We linked CH cases with MACDP records to ascertain the presence of serious birth defects among infants with CH. Of 97 infants identified with CH through newborn screening and/or MACDP (1:5,000 live births), 87 had primary CH and 10 had secondary. T he rate of primary CH was higher among nonhispanic whites than among b lacks (1:4,400 vs, 1:10,000) and among females compared with males (1: 4,000 vs, 1:7,700), Among infants with primary CH, 77 had isolated CH, 3 had Down syndrome, and 7 had unrelated major structural defects. Ba sed on Atlanta population rates of Down syndrome and major structural anomalies, we infer i) infants with Down syndrome have a 35-fold incre ased risk for primary CH compared with infants in the general populati on (P < .0001); ii) infants with primary CH have a 2.2-fold increased risk for major structural anomalies (P < .05). Because this is the fir st population study of CH in the United States in which data from two population-based registries were linked, the epidemiologic patterns an d associated defects are more representative than those found in studi es based on newborn screening records only. (C) 1997 Wiley-Liss, Inc.