Diabetes in Pregnancy

Diabetes in pregnancy From Dr W P Kennedy Edinburgh EH4 1QA Dear Sir, The symposium on diabetes in pregnancy (March Journal, pp 202-222) deserves special comment. The neatly complimentary papers from King's College Hospital and Birmingham General Hospitalnotable centres of research in this field are compact, informative and seminal. They will interest not only the specialist but also the general physician. I first started research under Sir Edward Sharpey Schafer who, before the discovery ofinsulin in 1921, had postulated a probable endocrine function for the islets of Langerhans. Then one evening in the mid twenties, despite my junior status, I had the privilege of being entertained by Professor J J R MacLeod, the mentor of Banting and Best, until I a.m., with the hciting story of the insulin discovery and a superlative Highland malt. While reading this symposium I thought of the enormous growth since then both of knowledge of the disease and of alleviation of its effects evidenced by these contributions. But since every advance can engender new problems, we realize that we have not got all the answers. Both P J Watkins and Professor Malins point out that the reason for the increase of congenital malformations in the infants of diabetic mothers is unknown; J M Brudenell mentions the unexplained intrauterine death in late pregnancy; and H R Gamsu states that we do not know the mechanism of polycythaemia in these babies. To those interested in birth defects these admissions are no surprise. The general view in teratological literature is that the cause of congenital malformations in man can only be ascribed accurately in about 40% ofcases, and even that figure may be too high if the distinction between cause and association is scrupulously made. It may be added that my working index on human teratology and fetal loss contains over 700 references to the lack of information about particular aspects of the many problems that beset researchers in these closely-linked fields. In the first paper, P J Watkins writes 'Established diabetics should be obsessionally controlled throughout pregnancy, if possible from the time of conception'; an admirable dictum, and 'obsessionally' is a particularly apt word in this context. He concludes that improved diabetic control in pregnancy is at least one of the factors responsible for the improvement in fetal survival, and surely no one will cavil at that. The other contributors to the symposium support his view. Watkins quotes White's 1935 paper in which she reported the mortality rate of the diabetic fetuses in the Joslin Clinic as being 28.5% which was then so Iowa figure that it raised considerable interest especially in America; and Professor Malins cites W E Henley's 1947 average of 40% from major European and American centres. It happened that, in connection with another project, I collected 27 papers on diabetic pregnancies between 1907 and 1950 in which the total births were 3336, the deaths were 955 and the loss rate averaged 28.5%. The numbers in the groups studied varied from 17to 459 cases, so comparison was not easy. Further, it seemed to me probable that differences in regimes and controls were wider then than now, and this might account for the wide spread of the results. The improvement that has been attained is shown by the fact that fetal losses between 1971 and 1976 at King's College Hospital were only 4.5%, and this result is supported by Professor Malins' statement that figures of 5-10% are current. He adds that the general management of pregnancy and the neonate have improved greatly in the past twenty years. Even so, the prognosis for the diabetic pregnancy is definitely much more favourable today than it was. This, too, is supported by J M Brudenell's results for perinatal mortality in diabetic pregnancies, which has fallen from 31.3%in 1951-55t03.4%in 1971-75. H R Gamsu also reports a significant reduction in morbidity, although the percentage of congenital malformations in the babies ofdiabetic mothers has not decreased in the past nine years. Altogether then, the symposium records real achievement that bodes well for the future. Yours sincerely wALTER P KENNEDY 23 February 1978