Congenital malformations and environmental influences in pregnancy.

Abstract

As part of an epidemiological study of congenital defects in South Wales from 1964-1966 a retrospective analysis was performed of 833 consecutive cases of malformations and an equal number of matched controls. Factors investigated for their relationship to congenital defects included: 1) illnesses in the first trimester; 2) drug usage during pregnancy; 3) personal attributes such as employment housing and height and weight and 4) miscellaneous and genetic attributes. Of particular interest were the results for salicylate administration miscellaneous drugs and maternal diet. Significant differences between cases and controls were found when first trimester salicylate intake was compared (p < .001 overall). Such intake was specifically related to defects of the central nervous system (p < .05) alimentary tract (p < .01) and talipes (p < .01) suggesting that either salicylates or the conditions for which they are given have a teratogenic effect. Comparisons based on administration of miscellaneous drugs including antiemetics were also significant (p < .001) and specifically related to cardiovascular system defects (p < .05) alimentary tract defects (p < .01) aortic defects (p < .05) cleft lip and/or palate (p < .001) and eye and ear defects (p < .05). Notable was the absence of significant differences for drugs taken in the second and third trimesters. A significant excess (p < .05) of diets judged imbalanced was found among cases of malformations and were specifically related to central nervous system defects (p < .01) anencephaly (p < .01) and spina bifida cystica (p < .05). Dietary deficiencies shown to have teratogenic effects are those of vitamins A and E thiamin riboflavin niacin panothenic acid and folic acid. Retrospective studies are often limited by subject or interviewer bias or lack of recall of events dosages and timing. However these factors are assumed to have played a negligible role in this study since statistically significant differences occurred only in first trimester results.