Feto‐Maternal Bleeding

Blood samples from pregnant women and from mothers before and after delivery were tested for the occurrence of feto-maternal bleeding (f.m.b.) using Kleihauers acid-elution technique and a counting technique described by Schneider. It was assumed that f.m.b. had occurred, when there was a clinically significant difference between the values of hb-F cells per million cells in two blood samples. F.m.b. had occurred in nearly 2/3 of the mothers after pregnancy and delivery. The f.m.b.'s were most often less than 0.1 ml and only a few per cent had f.m.b.'s between 0.1 and 1 ml. Abortion, complicated pregnancies, amniocentesis, pre-eclampsia, caesarean section and other kinds of complicated deliveries increased the risk of especially larger f.m.b.'s.