Research Article Research on the fetus. Br Med J 1972; 2 doi: https://doi.org/10.1136/bmj.2.5813.550-a (Published 03 June 1972) Cite this as: Br Med J 1972;2:550 Article Related content Metrics Responses Peer review This article has corrections. Please see:Is Your Pain Really Necessary? - June 09, 1973 Nutritional Macrocytic Anaemia: Correction - October 27, 1945 This is a PDF-only article. The first page of the PDF of this article appears below.