Risk factors for coarctation of the aorta.

To test the hypothesis that environmental factors during early pregnancy may cause coarctation of the aorta (CoA), 50 cases of CoA and 756 controls were studied. The cases represented all verified CoAs in Finland during 1982-1983 and controls were randomly selected from all babies born during the same period. Both case and control mothers were interviewed by midwives approximately 3 months after delivery. In these data 18 patients had pure CoA only and the remaining 32 at least one other cardiac anomaly. Three CoA patients had a chromosomal anomaly. The relatives of CoA babies had more congenital anomalies than those of the control babies. Maternal overall exposure to chemicals at work was slightly more prevalent among the CoA group (32.0%) than the control group (26.2%). Maternal exposure to mineral oil products at work during early pregnancy was more common among CoA cases (8.0%) than controls (1.4%) [odds ratio (OR) = 5.9, 95% confidence interval (CI95) = 1.8-19.2]. The risk of CoA was also associated with previous miscarriages (OR = 2.3, CI95 = 1.2-4.4) and twin birth (OR = 16.3, CI95 = 4.0-67) of the child. The risk of CoA was not associated with seasonal variation, maternal smoking, alcohol consumption, or use of deodorants. It is concluded that genetic factors explain only a small fraction of the causes of CoA and that many common environmental exposures during early pregnancy are unlikely to be real risk factors for CoA. However, the power of this study was weak for testing the teratogenicity of specific chemicals.