In 152 consecutively observed mothers who had delivered malformed infants intheir last pregnancy, 10 per cent had abnormal standard glucose tolerance tests and 45 per cent abnormal triamcinolone glucose tolerance tests. These findings are in contrast to a 3.3 per cent prevalence of abnormal triamcinolone glucose tolerance tests in a controlled group selected for absence of findings suggesting diabetes. The observation suggests that a relation exists between carbohydrate disturbance and the delivery of malformed infants.