The possible effects of genetic and environmental risk factors during pregnancy on the occurrence of cardiovascular malformations in the offspring was studied in 408 cases and 756 controls. The cases represented all registered cardiovascular malformations reported in Finland during 1982-1983. The controls were randomly selected from all babies born during the same period. Both the case and control mothers were interviewed by midwives approximately three months after delivery using a structured questionnaire. The parents of cases had more cardiovascular malformations than parents of the controls. Maternal alcohol consumption seemed to double the risk of atrial septal defect (OR = 1.9, CI95 1.0-3.4). Maternal exposure to dyes, lacquers or paints was a significant risk factor for conal septal defects (OR = 2.9, CI95 = 1.2-7.5). Maternal upper respiratory infection was twice as common among the hypoplastic left ventricle group as among the controls. Maternal smoking, coffee, tea and cola consumption and intake of acetylsalicylic acid were equally prevalent in both groups. Maternal exposure to anesthetic gases, wood preservatives or pesticides was not associated with the risk of cardiovascular malformations. The study confirms that very little is known of the etiology of congenital heart disease.

During pregnancy, a number of factors predisposing to hyperthermia, such as sleeping in a water bed, sauna bathing, heatwave, high workplace temperature, and fever, are believed capable of harming the foetus. This study aimed to clarify possible associations of maternal workplace temperature, season of birth, sauna bathing, upper respiratory infection, and fever, with cardiovascular malformations in the offspring. The material was composed of all 573 cardiac malformations registered in Finland in 1982-84, and 1055 randomly chosen healthy controls. The mothers were interviewed at maternity welfare centers about three months after delivery. Fever (greater than or equal to 38 degrees C) during early pregnancy was more prevalent among case mothers (10%) than controls (6%) (p less than 0.01), largely manifest as increased risks of atrial septal defect and hypoplastic left heart. Upper respiratory infection was also more common among case mothers (26%) than controls (18%) (p less than 0.001). By contrast, maternal workplace temperature, sauna bathing, and temperature of the environment (seasonal variation) were not associated with risk of cardiac malformation in the offspring. The use of acetylsalicylic acid-containing medication for reducing fever was equally common (7%) among case and control mothers.

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